Transdermal analyte sensor, applicator therefor, and related method

Abstract

This invention provides a system and method for applying a transdermal analyte measurement system to recipients. [Solution] This embodiment relates, in general, to applicators for skin sensor assemblies for measuring analytes within a recipient, as well as to methods for using and manufacturing them. In some embodiments, an applicator is provided for applying a skin sensor assembly to the skin of a recipient. The applicator comprises an applicator housing; a needle carrier assembly including an insertion element configured to insert the sensor of the skin sensor assembly into the skin of the recipient; a holder releasably coupled to the needle carrier assembly and configured to guide the skin sensor assembly while coupled to the needle carrier assembly; and a drive assembly configured to drive the insertion element from a proximal starting position to a distal insertion position and from the distal insertion position to a proximal retraction position.

Description

Technical Field

[0001] Incorporation by reference to related applications All priority claims identified in the application data sheet, or any amendments thereto, are hereby incorporated by reference into this specification under 37 C.F.R. § 1.57. This application claims the benefit of U.S. Provisional Patent Application No. 62 / 524,247, filed Jun. 23, 2017, and U.S. Provisional Patent Application No. 62 / 658,486, filed Apr. 16, 2018. Each of the foregoing applications is hereby incorporated by reference in its entirety and made a part hereof as if fully set forth herein.

[0002] Systems and methods are provided for measuring an analyte within a recipient. More specifically, systems and methods are provided for applying a transdermal analyte measurement system to a recipient.

Background Art

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

[0004] Traditionally, people with diabetes have carried self-monitoring blood glucose (SMBG) monitors, which typically require an uncomfortable finger-prick method. Due to the lack of comfort and convenience, people with diabetes usually only measure their glucose levels two to four times a day. Unfortunately, such time intervals are too far apart, which can lead to people with diabetes becoming aware of hyperglycemia or hypoglycemia too late, sometimes resulting in dangerous side effects. Glucose levels can, however, be continuously monitored by a sensor system, which may include a skin sensor assembly. The sensor system may have a wireless transmitter that sends measurement data to a receiver, which can process and display information based on the measurements. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The process of applying sensors to people is crucial for such systems to be effective and easy to use. The application process should result in a sensor assembly that can be attached to a person, capable of detecting glucose level information, communicating the detected data to a transmitter, and transmitting the glucose level information to a receiver.

[0006] This background technology is provided to introduce a concise context for the following outline of the invention and for embodiments for carrying out the invention. This background technology is not intended to assist in determining the scope of the subject matter described in the claims, nor is it intended to limit the subject matter described in the claims to any implementation that solves any or all of the above disadvantages or problems. [Means for solving the problem]

[0007] This system and method relates to a system and method for measuring analytes within a recipient and for applying a transdermal analyte measurement system to a recipient. Various embodiments of this system and method for applying an analyte measurement system have several features, none of which individually contribute to their desired attributes. Without limiting the scope of this embodiment as expressed by the following claims, some of their more prominent features are briefly discussed here. After considering this discussion, and especially after reading the section titled “Modes for Carrying Out the Invention,” you will understand how the features of this embodiment provide the advantages described herein.

[0008] An applicator is provided for applying a skin sensor assembly to the skin of a recipient. The applicator comprises an applicator housing; a needle carrier assembly including an insertion element configured to insert the sensor of the skin sensor assembly into the skin of a recipient; a holder releasably coupled to the needle carrier assembly and configured to guide the skin sensor assembly while coupled to the needle carrier assembly; and a drive assembly configured to drive the insertion element from a proximal starting position to a distal insertion position and from the distal insertion position to a proximal retraction position.

[0009] In some embodiments, the skin sensor assembly includes an electronic unit. In some embodiments, the sensor is connected to the electronic unit within an applicator housing. In some embodiments, a holder is configured to release the skin sensor assembly after the sensor has been at least partially inserted into the recipient's skin. In some embodiments, the applicator further includes an actuation element configured to actuate a drive assembly. In some embodiments, the actuation element includes a deflectable feature. In some embodiments, the deflectable feature is configured to provide resistance to actuation. In some embodiments, the deflectable feature is configured to return the actuation element to its starting position. In some embodiments, the actuation element includes one of a button, switch, toggle, slide, trigger, and knob. In some embodiments, the applicator further includes a safety element configured to prevent the actuation element from operating. In some embodiments, the safety element includes a tab coupled to the actuation element by at least one easily breakable member. In some embodiments, the distal and proximal directions extend along the insertion axis of the insertion element. In some embodiments, the holder includes an elastomer.

[0010] In a first embodiment, the applicator housing includes a guide. The drive assembly includes a rotary drive element coupled to the needle carrier assembly, a pin configured to move within the guide during rotation of the rotary drive element, and a spring configured to rotate the rotary drive element in a single rotational direction when the drive assembly is operated, thereby driving the insertion element from a proximal starting position to a distal insertion position and from the distal insertion position to a proximal retraction position. In some embodiments, the rotary drive element is configured to convert rotational motion into linear motion. In some embodiments, the rotary drive element includes a wheel cam. In some embodiments, the pin is radially offset from the axis of rotation of the rotary drive element. In some embodiments, the pin is positioned approximately 30 degrees from the lower center orientation with respect to the axis of rotation of the rotary drive element when the insertion element is in the proximal starting position. In some embodiments, the pin is positioned approximately 180 degrees from the lower center orientation with respect to the axis of rotation of the rotary drive element when the insertion element is in the distal insertion position. In some embodiments, the pin is positioned approximately 330 degrees from the lower center orientation with respect to the axis of rotation of the rotary drive element when the needle carrier assembly is in the proximal retracted position. In some embodiments, the pin moves within the guide in a direction perpendicular to the extension direction of the insertion element. In some embodiments, the guide includes a slot. In some embodiments, the slot is stationary during sensor insertion. In some embodiments, the slot includes a horizontal slot. In some embodiments, the slot includes a vertical slot configured to receive at least the pin of the rotary drive element when loaded through the bottom of the applicator housing. In some embodiments, the applicator housing is stationary. In some embodiments, the rotary drive element further includes a projection that contacts a retaining element configured to prevent the rotary drive element from rotating. In some embodiments, the applicator further includes an actuating element configured to deflect the retaining element, thereby allowing the rotary drive element to rotate. In some embodiments, the rotary drive element further includes a projection configured to separate the on-skin sensor assembly from the needle carrier assembly.In some embodiments, the projection is configured to apply force to the skin sensor assembly while the rotary drive element is rotating. In some embodiments, the projection of the rotary drive element is configured to pass through a slot in the needle carrier assembly as the rotary drive element rotates.

[0011] In a second embodiment, the drive assembly includes a torsion spring. The torsion spring includes a first end coupled to the applicator housing and a second end coupled to the needle carrier assembly. When the drive assembly is operated, the first and second ends are unwound in opposite directions, thereby driving the insertion element from the proximal starting position to the distal insertion position and from the distal insertion position to the proximal retraction position. In some embodiments, the first and second ends are unwound in opposite directions to drive the torsion spring in an arc. In some embodiments, the arc extends in directions perpendicular to the distal and proximal directions. In some embodiments, a spool is provided coupled to the torsion spring. In some embodiments, the torsion spring is wound around the spool. In some embodiments, the second end of the torsion spring is configured to drive the insertion element. In some embodiments, the torsion spring is a double torsion spring. In some embodiments, the first end of the torsion spring is coupled to a projection of the applicator housing. In some embodiments, the second end of the torsion spring is coupled to a projection of the needle carrier assembly.

[0012] In a third embodiment, the drive assembly further includes a connecting element comprising a first end coupled to the first end of the torsion spring, a second end coupled to the second end of the torsion spring, and a hinge substantially aligned with the winding axis of the torsion spring. In some embodiments, the connecting element includes a flexible connecting portion.

[0013] In a fourth embodiment, the drive assembly includes a coupling element, which includes a first end coupled to the applicator housing, a second end coupled to the needle carrier assembly, and a hinge disposed between the first and second ends. The drive assembly further includes a torsion spring, which includes a first end coupled to the needle carrier assembly and a second end coupled to the coupling element between the second end and the hinge. When the drive assembly is actuated, the second end is configured to drive the coupling element such that the insertion element is driven from a proximal start position to a distal insertion position and from the distal insertion position to a proximal retraction position.

[0014] In a fifth embodiment, the drive assembly includes a coupling element comprising a first end coupled to the applicator housing, a second end coupled to the needle carrier assembly, and a hinge disposed between the first and second ends. The drive assembly further includes a torsion spring comprising a first end coupled to the applicator housing and a second end coupled to the coupling element between the first end and the hinge. When the drive assembly is actuated, the second end is configured to drive the coupling element such that the insertion element is driven from a proximal start position to a distal insertion position and from the distal insertion position to a proximal retraction position.

[0015] In a sixth embodiment, the drive assembly includes a coupling element comprising a first end coupled to an applicator housing, a second end coupled to a needle carrier assembly, and a hinge disposed between the first and second ends. The drive assembly further includes a tension spring coupled to the coupling element. When the drive assembly is actuated, the tension spring is configured to drive the coupling element such that the insertion element is driven distally to a distal insertion position and from the distal insertion position proximally.

[0016] In a seventh embodiment, the drive assembly includes a leaf spring having a first end coupled to the applicator housing and a second end coupled to the needle carrier assembly. When the drive assembly is actuated, the leaf spring is configured to be uncompressed, thereby driving the insertion element at least distally to the distal insertion position.

[0017] In the eighth aspect, the drive assembly includes a coupling element, which includes a first end coupled to the applicator housing, a second end coupled to the needle carrier assembly, and a hinge disposed between the first and second ends. The drive assembly further includes a leaf spring, which includes a first end coupled to the needle carrier assembly and a second end coupled to the coupling element between the second end and the hinge. When the drive assembly is actuated, the leaf spring is decompressed, thereby driving the insertion element distally to a distal insertion position and from the distal insertion position proximal.

[0018] In the ninth embodiment, the drive assembly includes a leaf spring having a first end coupled to the applicator housing and a second end coupled to the needle carrier assembly. When the drive assembly is actuated, the leaf spring is configured to be uncompressed, thereby driving the insertion element at least distally to the distal insertion position.

[0019] In a tenth embodiment, the drive assembly includes a coupling element comprising a first end coupled to the applicator housing, a second end coupled to the needle carrier assembly, and a hinge disposed between the first and second ends. The drive assembly further includes a leaf spring comprising a first end coupled to the needle carrier assembly and a second end coupled to the coupling element between the second end and the hinge. When the drive assembly is actuated, the leaf spring is decompressed, thereby driving the insertion element distally to a distal insertion position and from the distal insertion position proximal.

[0020] In an eleventh embodiment, the drive assembly includes an insertion spring configured to drive the insertion element distally to a distal insertion position when the drive assembly is actuated, and a retraction spring configured to contact the needle carrier assembly and drive the insertion element from the distal insertion position to a proximal retraction position. In some embodiments, the insertion spring includes a compression spring. In some embodiments, the retraction spring includes a leaf spring. In some embodiments, the retraction spring is configured to retract the insertion element from the recipient's skin. In some embodiments, when the drive assembly is actuated, a portion of the energy stored in the insertion spring is transferred to the retraction spring when the insertion spring drives the insertion element distally. In some embodiments, the insertion spring includes a first end coupled to the applicator housing and a second end coupled to a holder, the holder coupled to the needle carrier assembly while the insertion spring drives the insertion element distally to a distal insertion position and disengaged from the needle carrier assembly when the retraction spring drives the insertion element proximal from the distal insertion position. In some embodiments, the insertion element is configured to move in an arc when driven in the distal and proximal directions.

[0021] In a twelfth embodiment, the drive assembly includes a rotary drive element comprising: a ridge configured to slide along a channel of the needle carrier assembly, defining a variable cam path around at least a portion of the rotary drive element; and a torsion spring configured to rotate the rotary drive element when the drive assembly is in operation, thereby driving the insertion element distally to a distal insertion position and proximal from the distal insertion position based on the variable cam path. In some embodiments, the torsion spring is configured to rotate the rotary drive element in a single direction by an angle greater than zero degrees and less than 360 degrees when the drive assembly is in operation. In some embodiments, the rotary drive element includes a barrel cam. In some embodiments, the rotary drive element is configured to rotate in a plane substantially perpendicular to the proximal and distal directions.

[0022] In a thirteenth embodiment, the drive assembly includes a guide member coupled to an applicator housing, and a hub configured to slide along the guide member, the hub contacting a reverse toggle element through a first moving portion along the guide member, and contacting a needle carrier assembly through a second moving portion along the guide member. The reverse toggle element includes a pivot point, a first end that contacts the hub through a first portion of movement along the guide member, and a second end coupled to the needle carrier assembly. The drive assembly further includes a spring configured, when the drive assembly is actuated, to drive the hub proximal through the first moving portion along the guide member, thereby driving the insertion element distally to a distal insertion position, and to drive the hub proximal through a second moving portion along the guide member, thereby driving the insertion element proximal from the distal insertion position.

[0023] In a fourteenth embodiment, the drive assembly includes a first spring configured to drive the needle carrier assembly distally to the distal insertion position when the drive assembly is actuated, and a second spring configured to drive the needle carrier assembly proximal from the distal insertion position. In some embodiments, the first and second springs are pre-compressed before the drive assembly is actuated. In some embodiments, when the needle carrier assembly is driven distally to the distal insertion position, at least a portion of the energy stored in the first spring is transferred to the second spring.

[0024] In some embodiments, the holder includes at least one retaining element configured to secure the holder to the applicator housing when the needle carrier assembly reaches the distal insertion position. In some embodiments, the holder releasably couples the surface sensor assembly to the holder as the needle carrier assembly moves distally to the distal insertion position, and detaches the surface sensor assembly from the holder as the needle carrier assembly moves proximal from the distal insertion position.

[0025] In some embodiments, the holder includes a retaining element that includes a first end and a second end. The first end is fixed within a guide of the needle carrier assembly such that when the needle carrier assembly moves distally to a distal insertion position, the second end releasably couples to the on-skin sensor assembly, and the first end disconnects the second end from the on-skin sensor assembly when the needle carrier assembly moves proximally from the distal insertion position and separates from the holder.

[0026] In some embodiments, the needle carrier assembly includes a retaining element that releasably couples the on-skin sensor assembly to the holder when the needle carrier assembly moves distally to a distal insertion position, and the retaining element is configured to deform sufficiently to disconnect from the on-skin sensor assembly when the needle carrier assembly moves proximally from the distal insertion position and separates from the holder.

[0027] In some embodiments, the holder includes a deformable retaining element that releasably couples the on-skin sensor assembly to the holder, and the needle carrier assembly contacts the deformable retaining element, thereby preventing the deformable retaining element from deforming when the needle carrier assembly moves distally to a distal insertion position. When the needle carrier assembly moves proximally from the distal insertion position, the needle carrier assembly separates from the holder, thereby enabling the retaining element to deform sufficiently to disconnect from the on-skin sensor assembly.

[0028] In some embodiments, the needle carrier assembly includes a first retaining element configured to releasably couple the holder to the needle carrier assembly, and a second retaining element configured to releasably couple the on-skin sensor assembly to one of the holder and the needle carrier assembly.

[0029] In some embodiments, the insertion element includes a C-shaped needle having a flared edge. In some embodiments, the insertion element includes a deflected tip needle. In some embodiments, the insertion element includes a needle having a curved shape configured to substantially follow the insertion path of the needle. In some embodiments, the insertion element includes a needle, and the needle carrier assembly further includes a needle hub configured as a pass-through for the needle during sensor insertion and further configured to surround the tip of the needle after sensor insertion. The insertion element further includes a needle spring configured to drive the needle hub to the tip of the needle after sensor insertion.

[0030] In some embodiments, a skin sensor assembly includes a filling port configured to receive a fluid or gel, and a cannula configured to deliver the fluid or gel through the skin of the recipient.

[0031] In some embodiments, the applicator further includes an elastomer sensor retaining element coupled to the applicator housing at a first end and coupled to at least one of the insertion element and the sensor. The elastomer sensor retaining element is configured to hold the sensor within the insertion element before the drive assembly is actuated. In some embodiments, the insertion element is configured to advance proximal so that the elastomer sensor retaining element is detached from at least one of the insertion element and the sensor.

[0032] In some embodiments, the applicator further includes a sensor retaining element, which includes a tab configured to hold the sensor within the insertion element before the drive assembly is activated.

[0033] In some embodiments, the applicator further includes a sensor retaining element configured to be positioned relative to at least one of the insertion element and the sensor in a first position, and to rotate away from the insertion element and the sensor in a second position.

[0034] In some embodiments, the applicator further includes an insertion element and a sensor retaining sleeve disposed around at least a portion of the sensor. The needle carrier assembly includes a tapered needle hub configured to split the sensor retaining sleeve during sensor insertion.

[0035] In some embodiments, the sensor includes a strain-relieving feature configured to limit the bending of the sensor to a bending radius smaller than a predetermined bending radius. In some embodiments, the strain-relieving feature includes an elastomer material.

[0036] In some embodiments, the skin sensor assembly includes an open cavity configured to receive the sensor and provide a region in which the sensor bends from substantially horizontal to substantially vertical. In some embodiments, the open cavity is configured to guide bodily fluids released from the recipient as a result of the sensor being inserted at least partially into the recipient's skin. In some embodiments, the skin sensor assembly includes a wicking material configured to absorb bodily fluids released from the recipient as a result of the sensor being inserted at least partially into the recipient's skin.

[0037] A 15th embodiment provides a method for applying a skin sensor assembly to the skin of a recipient. The method includes providing an applicator comprising an applicator housing, a needle carrier assembly including an insertion element configured to insert the sensor of the skin sensor assembly into the skin of a recipient, a holder releasably coupled to the needle carrier assembly and configured to guide the skin sensor assembly while coupled to the needle carrier assembly, a drive assembly, and an actuation element. The method includes acting the actuation element, which causes the drive assembly to drive the insertion element distally to a distal insertion position and from the distal insertion position proximal to a proximal retraction position, thereby inserting the sensor of the skin sensor assembly at least partially into the skin of a recipient. In some embodiments, the distal and proximal directions extend along the insertion axis of the insertion element.

[0038] In some embodiments, the applicator housing includes a guide. The drive assembly includes a rotary drive element coupled to the needle carrier assembly, a pin configured to move within the guide during rotation of the rotary drive element, and a spring configured to rotate the rotary drive element in a single rotational direction when the drive assembly is operated, thereby driving the insertion element from the proximal starting position to the distal insertion position and from the distal insertion position to the proximal retraction position. In some embodiments, the rotary drive element is configured to convert rotational motion into linear motion. In some embodiments, the rotary drive element includes a wheel cam. In some embodiments, the pin is radially offset from the rotation axis of the rotary drive element. In some embodiments, the pin is positioned approximately 30 degrees from the lower center orientation with respect to the rotation axis of the rotary drive element when the insertion element is in the proximal starting position. In some embodiments, the pin is positioned approximately 180 degrees from the lower center orientation with respect to the rotation axis of the rotary drive element when the insertion element is in the distal insertion position. In some embodiments, the pin is positioned approximately 330 degrees from the lower central orientation with respect to the axis of rotation of the rotary drive element when the needle carrier assembly is in the proximal retracted position. In some embodiments, the guide includes a slot.

[0039] In some embodiments, the drive assembly includes a torsion spring, which includes a first end coupled to the applicator housing and a second end coupled to the needle carrier assembly. When the drive assembly is actuated, the first and second ends are unwound in opposite directions, thereby driving the insertion element from the proximal starting position to the distal insertion position and from the distal insertion position to the proximal retraction position. In some embodiments, the first and second ends are unwound in opposite directions to drive the torsion spring in an arc. In some embodiments, the arc extends in directions perpendicular to the distal and proximal directions.

[0040] In some embodiments, the drive assembly includes an insertion spring configured to drive the insertion element distally to a distal insertion position when the drive assembly is actuated, and a retraction spring configured to contact the needle carrier assembly and drive the insertion element from the distal insertion position to a proximal retraction position. In some embodiments, the insertion spring is a compression spring. In some embodiments, the retraction spring is a leaf spring. In some embodiments, when the drive assembly is actuated, a portion of the energy stored in the insertion spring is transferred to the retraction spring when the insertion spring drives the insertion element distally. In some embodiments, the insertion spring includes a first end coupled to the applicator housing and a second end coupled to a holder. The holder is coupled to the needle carrier assembly while the insertion spring drives the insertion element distally to a distal insertion position and is disconnected from the needle carrier assembly when the retraction spring drives the insertion element proximal from the distal insertion position. In some embodiments, the insertion element is configured to move in an arc when driven distally and proximal.

[0041] In some embodiments, the drive assembly includes a rotary drive element comprising: a ridge configured to slide along a channel of the needle carrier assembly, defining a variable cam path around at least a portion of the rotary drive element; and a torsion spring configured to rotate the rotary drive element when the drive assembly is actuated, thereby driving the insertion element distally to a distal insertion position and proximal from the distal insertion position based on the variable cam path. In some embodiments, the torsion spring is configured to rotate the rotary drive element in a single direction by an angle greater than zero degrees and less than 360 degrees when the drive assembly is actuated. In some embodiments, the rotary drive element includes a barrel cam. In some embodiments, the rotary drive element is configured to rotate in a plane substantially perpendicular to the proximal and distal directions.

[0042] In some embodiments, the drive assembly includes a guide member coupled to an applicator housing, and a hub configured to slide along the guide member, the hub contacting a reverse toggle element through a first moving portion along the guide member, and contacting a needle carrier assembly through a second moving portion along the guide member. The reverse toggle element includes a pivot point, a first end that contacts the hub through a first portion of movement along the guide member, and a second end coupled to the needle carrier assembly. The drive assembly further includes a spring configured, when the drive assembly is actuated, to drive the hub proximal through the first moving portion along the guide member, thereby driving the insertion element distally to a distal insertion position, and to drive the hub proximal through a second moving portion along the guide member, thereby driving the insertion element proximal from the distal insertion position.

[0043] In some embodiments, the drive assembly includes a first spring configured to drive the needle carrier assembly distally to the distal insertion position when the drive assembly is actuated, and a second spring configured to drive the needle carrier assembly proximal from the distal insertion position. In some embodiments, when the needle carrier assembly is driven distally to the distal insertion position, at least a portion of the energy stored in the first spring is transferred to the second spring.

[0044] In a sixteenth embodiment, an applicator is provided for applying a cutaneous sensor assembly to the skin of a recipient. The applicator includes an insertion assembly configured to translate the needle carrier assembly and the cutaneous sensor assembly distally from an initial proximal position to a distal insertion position. The applicator includes a retraction assembly configured to translate the needle carrier assembly proximal from the distal insertion position to a proximal retraction position. The retraction assembly is configured to act in response to the cutaneous sensor assembly coming into contact with the skin of a recipient.

[0045] In some embodiments, the insertion assembly includes a first spring. In some embodiments, the retraction assembly includes a second spring. In some embodiments, the insertion assembly further includes a holder configured to guide the needle carrier assembly during translation from at least an initial proximal position to a distal insertion position. In some embodiments, the holder further includes at least one retaining element configured to hold the second spring at least during insertion. In some embodiments, the at least one retaining element is disposed along the outside of the second coil and configured to contact and hold the coil of the second spring. In some embodiments, the needle carrier assembly further includes at least one backstop feature configured to prevent lateral deflection of at least one retaining element at least during insertion. In some embodiments, the at least one backstop feature is configured not to contact at least one retaining element at the distal insertion position, thereby allowing the second spring to deflect at least one retaining element and actuate the retraction assembly. In some embodiments, a second spring is configured to exert sufficient force to deflect at least one retaining element at the distal insertion position when the skin sensor assembly is in contact with the recipient's skin. In some embodiments, the applicator further includes an inner housing. In some embodiments, the applicator further includes an outer housing which includes an actuating element configured to actuate the insertion assembly. In some embodiments, the actuating element prevents the insertion assembly from acting until the outer housing has translated a predetermined distance distally relative to the inner housing. In some embodiments, the inner housing further includes an engaging element, and the needle carrier assembly includes a projection. The engaging element is configured to engage with the projection when the needle carrier assembly has translated distally beyond a predetermined threshold, thereby preventing the needle carrier assembly from translating distally beyond the predetermined threshold. In some embodiments, the engaging feature includes a hook. In some embodiments, the needle carrier assembly further includes a hub configured to connect the insertion element to the needle carrier assembly.In some embodiments, the hub is further configured to be coupled to a skin-borne sensor assembly.

[0046] In some embodiments, both the insertion assembly and the retraction assembly include a first spring. In some embodiments, the first spring is configured to exert force between the holder and the deployment sleeve. In some embodiments, the holder includes at least one retaining element configured to secure the holder to the deployment sleeve. In some embodiments, the applicator further includes a housing and an actuating element configured to deflect at least one retaining element, thereby allowing the first spring to translate the holder, needle carrier assembly, and cutaneous sensor assembly from a proximal position to a distal insertion position. In some embodiments, the housing further includes at least one projection, and the deployment sleeve includes at least one retaining element configured to contact at least one projection of the housing. In some embodiments, the first spring is configured to exert sufficient force to deflect at least one retaining element of the deployment sleeve when the cutaneous sensor assembly contacts the recipient's skin, thereby releasing at least one retaining element of the deployment sleeve from at least one projection of the housing. In some embodiments, the first spring is further configured to translate the deployment sleeve in the proximal direction. In some embodiments, the needle carrier assembly further includes a projection configured to contact the deployment sleeve and thereby translate the needle carrier assembly in the proximal direction.

[0047] In the 17th embodiment, a needle hub is provided for applying a skin sensor assembly to the skin of a recipient. The needle hub includes at least one upper arm. The needle hub includes a base which includes an anti-rotation feature. The base is configured to be at least partially positioned in an opening of the skin sensor assembly. The needle hub is configured to be coupled with an insertion element.

[0048] In some embodiments, the anti-rotation feature is configured to prevent the base from rotating within the opening. In some embodiments, the anti-rotation feature includes a key having a shape that complements at least a portion of the opening. In some embodiments, at least one upper arm is configured to be disposed through the opening of the needle carrier assembly of the applicator. In some embodiments, at least one upper arm is configured to contact the upper surface of the needle carrier assembly adjacent to the opening of the needle carrier assembly. In some embodiments, at least one upper arm is disposed in a groove on the upper surface of the needle carrier assembly, thereby configuring to secure the needle hub to the needle carrier assembly. In some embodiments, at least one upper arm is flexible. In some embodiments, at least one upper arm is configured to bend radially inward. In some embodiments, the needle hub further includes at least one lower arm. In some embodiments, at least one lower arm is configured to contact the lower surface of the needle carrier assembly adjacent to the opening of the needle carrier assembly. In some embodiments, the insertion element includes a needle. In some embodiments, the needle includes an open end configured to receive a sensor of a skin sensor assembly. In some embodiments, the base includes a flat surface configured to mate with the top surface of the skin sensor assembly, thereby maintaining the insertion element in an orientation substantially perpendicular to the top surface of the skin sensor assembly.

[0049] In the 18th embodiment, a method is provided for applying a cutaneous sensor assembly to the skin of a recipient. The method includes the step of providing an applicator. The applicator includes a housing containing an actuating element. The applicator includes an insertion assembly. The applicator includes a retraction assembly. The method includes the step of actinguating the actuating element. The step of actinguating the actuating element causes the insertion assembly to translate the needle carrier assembly and the cutaneous sensor assembly distally from a proximal position to a distal insertion position, thereby causing the sensor of the cutaneous sensor assembly to be at least partially inserted into the skin of the recipient. The step of actinguating the actuating element causes the retraction assembly to translate the needle carrier assembly proximal from a distal insertion position to a proximal retraction position. The retraction assembly is configured to actuate in response to the cutaneous sensor assembly coming into contact with the skin of the recipient.

[0050] In some embodiments, the insertion assembly includes a first spring. In some embodiments, the retraction assembly includes a second spring. In some embodiments, the insertion assembly further includes a holder configured to guide the needle carrier assembly during translation from at least a proximal position to a distal insertion position. In some embodiments, the holder further includes at least one retaining element configured to hold the second spring at least during insertion. In some embodiments, the at least one retaining element is disposed along the outside of the second coil and configured to contact and hold the coil of the second spring. In some embodiments, the needle carrier assembly further includes at least one backstop feature configured to prevent lateral deflection of at least one retaining element at least during insertion. In some embodiments, the at least one backstop feature is configured not to contact at least one retaining element at the distal insertion position, thereby allowing the second spring to deflect at least one retaining element and actuate the retraction assembly. In some embodiments, a second spring is configured to exert sufficient force to deflect at least one retaining element at the distal insertion position when the skin sensor assembly is in contact with the recipient's skin. In some embodiments, the second spring includes a tongue extending along the diameter of the second spring, and at least one retaining element is disposed along the inside of the second spring and configured to hold the tongue of the second spring. In some embodiments, the housing is an outer housing, and the applicator further includes an inner housing. In some embodiments, the step of actinguating the actuating element includes the step of translating the outer housing distally by a predetermined distance relative to the inner housing. In some embodiments, the inner housing further includes an engaging element, and the needle carrier assembly includes a projection. The engaging element is configured to engage with the projection when the needle carrier assembly is translated distally beyond a predetermined threshold, thereby preventing the needle carrier assembly from being translated distally beyond the predetermined threshold. In some embodiments, the engaging feature includes a hook.In some embodiments, the needle carrier assembly further includes a needle hub configured to connect an insertion element to the needle carrier assembly.

[0051] In some embodiments, both the insertion assembly and the retraction assembly include a first spring. In some embodiments, the first spring is configured to exert force between the holder and the deployment sleeve. In some embodiments, the holder includes at least one retaining element configured to secure the holder to the deployment sleeve. In some embodiments, the step of acting the actuating element includes deflecting at least one retaining element of the holder, thereby allowing the first spring to translate the holder, needle carrier assembly, and cutaneous sensor assembly from a proximal position to a distal insertion position. In some embodiments, the housing further includes at least one projection, and the deployment sleeve includes at least one retaining element configured to contact at least one projection of the housing. In some embodiments, the first spring is configured to exert sufficient force to deflect at least one retaining element of the deployment sleeve when the cutaneous sensor assembly contacts the recipient's skin, thereby releasing at least one retaining element of the deployment sleeve from at least one projection of the housing. In some embodiments, the first spring is further configured to translate the deployment sleeve in the proximal direction. In some embodiments, the needle carrier assembly further includes a projection configured to contact the deployment sleeve and thereby translate the needle carrier assembly in the proximal direction.

[0052] In a 19th embodiment, an applicator is provided for applying a skin sensor assembly to the skin of a recipient. The applicator includes a first body releasably coupled to a needle. The applicator further includes a second body releasably coupled to the first body by a friction engagement. The applicator further includes a spring configured to provide a first force to the first and second bodies. The first force can drive the first and second bodies distally. The friction engagement may be configured to be disengaged by a reaction force applied to the skin sensor assembly in the opposite direction to the first force.

[0053] In some embodiments, the applicator further includes at least one retaining element configured to frictionally couple a second body to a first body. In some embodiments, the at least one retaining element is integrally formed with the second body. In some embodiments, the at least one retaining element frictionally engages with a wall of the first body. In some embodiments, a reaction force disengages the frictional engagement by displacing the at least one retaining element from the wall of the first body. In some embodiments, the wall is a backstop. In some embodiments, the wall is configured to prevent the at least one retaining element from deflecting.

[0054] In some embodiments, the friction engagement is disengaged by a reaction force exceeding a force threshold. In some embodiments, the force threshold is determined by the frictional force between at least one retaining element and the first body. In some embodiments, the threshold is at least 0.5 lbf. In some embodiments, the threshold is at least 1 lbf.

[0055] In some embodiments, the first body is configured to retract proximally when disengaging the friction engagement. In some embodiments, the applicator further includes a second spring. The second spring may be configured to drive the first body proximally. In some embodiments, the second spring is held from release by at least one retaining element of the second body.

[0056] In some embodiments, the disengagement of the friction engagement is configured independently of the distance between the skin sensor assembly and the distal end of the applicator. In some embodiments, the first body is configured to retract independently of the distance between the skin sensor assembly and the distal end of the applicator. In some embodiments, the reaction force applied to the skin sensor assembly is provided by the recipient's skin resisting the first force. In some embodiments, the interior of the applicator is configured to allow the recipient's skin to be present inside. In some embodiments, the needle is configured to be inserted into the skin to a predetermined depth. In some embodiments, the friction engagement is configured to disengage over a range of distances between the skin sensor assembly and the distal end of the applicator.

[0057] This summary of the invention is provided to introduce a selection of concepts that are further described in the detailed description section. Other elements or steps may be conceivable, and no elements or steps are necessarily required. This summary is not intended to identify any major or essential features of the subject matter described in the claims, nor is it intended to be used as an aid in determining the scope of the subject matter described in the claims. The subject matter described in the claims is not limited to any implementation that resolves any or all of the disadvantages described in any part of this disclosure. [Brief explanation of the drawing]

[0058] These and other features, embodiments, and advantages are described below with reference to the drawings, and are intended to be illustrative rather than limiting to the present invention. In the drawings, similar reference letters consistently indicate the corresponding features throughout similar embodiments.

[0059] [Figure 1] Schematic diagrams of continuous analyte sensor systems according to several embodiments are shown. [Figure 2A]Perspective views of skin-surface sensor assemblies according to several embodiments are shown. [Figure 2B] Perspective views of skin-surface sensor assemblies according to several embodiments are shown. [Figure 3A] A perspective view of another skin sensor assembly according to several embodiments is shown. [Figure 3B] A perspective view of another skin sensor assembly according to several embodiments is shown. [Figure 4] Figures 3A and 3B show cross-sectional views of skin-surface sensor assemblies according to several embodiments. [Figure 5] Figure 5 shows exploded perspective views of the applicator according to several embodiments. [Figure 6A] Figure 5 shows perspective views of some feature parts of the applicator according to several embodiments. [Figure 6B] Figure 5 shows cross-sectional views of some feature parts of the applicator according to several embodiments. [Figure 6C] Figure 5 shows cross-sectional views of some feature parts of the applicator according to several embodiments. [Figure 6D] Figure 5 shows perspective views of some feature parts of the applicator according to several embodiments. [Figure 6E] Figure 5 shows perspective views of some feature parts of the applicator according to several embodiments. [Figure 6F] Figure 5 shows perspective views of some feature parts of the applicator according to several embodiments. [Figure 6G] Figure 5 shows cross-sectional views of some feature parts of the applicator according to several embodiments. [Figure 6H] Figure 5 shows cross-sectional views of some feature parts of the applicator according to several embodiments. [Figure 7A] Cross-sectional views of the applicator shown in Figure 5 during operation are shown according to several embodiments. [Figure 7B] Cross-sectional views of the applicator shown in Figure 5 during operation are shown according to several embodiments. [Figure 7C]Cross-sectional views of the applicator shown in Figure 5 during operation are shown according to several embodiments. [Figure 7D] Cross-sectional views of the applicator shown in Figure 5 during operation are shown according to several embodiments. [Figure 7E] Cross-sectional views of the applicator shown in Figure 5 during operation are shown according to several embodiments. [Figure 7F] Cross-sectional views of the applicator shown in Figure 5 during operation are shown according to several embodiments. [Figure 8] Figure 5 shows a cross-sectional view of an applicator similar to the applicator shown, but in some embodiments, the operating element is located on the upper side of the applicator housing. [Figure 9] Figure 5 shows a cross-section of an applicator similar to the applicator shown, but some embodiments include an operating element on the inside of the applicator housing. [Figure 10] Figure 5 shows a cross-sectional view of an applicator similar to the applicator shown, but some embodiments include an operating element on the lower side of the applicator housing. [Figure 11A] Figure 5 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 11B] Figure 5 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 11C] Figure 5 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 11D] Figure 5 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 11E] Figure 5 shows side cross-sectional views of the steps for assembling the applicator according to several embodiments. [Figure 11F] Figure 5 shows side cross-sectional views of the steps for assembling the applicator according to several embodiments. [Figure 11G-11H] Figure 5 shows side cross-sectional views of the steps for assembling the applicator according to several embodiments. [Figure 11J]Figure 5 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 12] An exploded perspective view of another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, is shown. [Figure 13A] The diagrams show cross-sectional views of some feature parts of the applicator shown in Figure 12, according to several embodiments. [Figure 13B] The diagrams show cross-sectional views of some feature parts of the applicator shown in Figure 12, according to several embodiments. [Figure 13C] The diagrams show cross-sectional views of some feature parts of the applicator shown in Figure 12, according to several embodiments. [Figure 13D] The diagrams show cross-sectional views of some feature parts of the applicator shown in Figure 12, according to several embodiments. [Figure 13E] Figure 12 shows perspective views of some feature parts of the applicator according to several embodiments. [Figure 13F] The diagrams show cross-sectional views of some feature parts of the applicator shown in Figure 12, according to several embodiments. [Figure 14A] Cross-sectional views of the applicator shown in Figure 12 during operation are shown according to several embodiments. [Figure 14B] Cross-sectional views of the applicator shown in Figure 12 during operation are shown according to several embodiments. [Figure 14C] Cross-sectional views of the applicator shown in Figure 12 during operation are shown according to several embodiments. [Figure 14D] Cross-sectional views of the applicator shown in Figure 12 during operation are shown according to several embodiments. [Figure 14E] Cross-sectional views of the applicator shown in Figure 12 during operation are shown according to several embodiments. [Figure 15] The following are perspective views of exemplary double torsion springs for use in applicators for skin sensor assemblies of analyte sensor systems, according to several embodiments. [Figure 16]A perspective view of another exemplary double torsion spring for use in an applicator for a skin sensor assembly of an analyte sensor system is shown, according to several embodiments. [Figure 17] A perspective view of yet another exemplary double torsion spring for use in an applicator for a skin sensor assembly of an analyte sensor system is shown, according to several embodiments. [Figure 18] Figure 12 shows cross-sectional views of alternative drive mechanisms, including torsion springs and living hinges, for the applicator according to several embodiments. [Figure 19] Figure 12 shows a cross-sectional view of another alternative drive mechanism, including a torsion spring and living hinge, for the applicator, according to several embodiments. [Figure 20] Figure 12 shows a cross-sectional view of yet another alternative drive mechanism, including a torsion spring and living hinge, according to several embodiments. [Figure 21] Figure 12 shows a cross-sectional view of yet another alternative drive mechanism, including a tension spring and living hinge, for the applicator, according to several embodiments. [Figure 22] Figure 12 shows a cross-section of yet another alternative drive mechanism, including a leaf spring for the applicator, according to several embodiments. [Figure 23] Figure 12 shows a cross-section of yet another alternative drive mechanism, including a leaf spring and living hinge, according to several embodiments. [Figure 24A] The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 24B] The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 24C] The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 24D] The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 24E]The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 24F] The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 24G] Figure 12 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 24H] The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 24J] The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 24K] Figure 12 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 24L] The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 24M] The following are cross-sectional views of the steps for assembling the applicator shown in Figure 12, according to several embodiments. [Figure 25] An exploded perspective view of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, is shown. [Figure 26A] Figure 25 shows sectioned perspective views of some feature parts of the applicator according to several embodiments. [Figure 26B] Figure 25 shows sectioned perspective views of some feature parts of the applicator according to several embodiments. [Figure 26C] Figure 25 shows sectioned perspective views of some feature parts of the applicator according to several embodiments. [Figure 26D] Figure 25 shows bottom views of some feature parts of the applicator according to several embodiments. [Figure 27A] Cross-sectional views of the applicator shown in Figure 25 in operation, according to several embodiments, are shown. [Figure 27B]Cross-sectional views of the applicator shown in Figure 25 in operation, according to several embodiments, are shown. [Figure 27C] Cross-sectional views of the applicator shown in Figure 25 in operation, according to several embodiments, are shown. [Figure 27D] Cross-sectional views of the applicator shown in Figure 25 in operation, according to several embodiments, are shown. [Figure 27E] Cross-sectional views of the applicator shown in Figure 25 in operation, according to several embodiments, are shown. [Figure 28A] Figure 25 shows perspective views of the applicator assembled according to several embodiments. [Figure 28B] Figure 25 shows perspective views of the applicator assembled according to several embodiments. [Figure 28C] Figure 25 shows perspective views of the applicator assembled according to several embodiments. [Figure 28D] Figure 25 shows cross-sectional views of the applicator assembled according to several embodiments. [Figure 28E] Figure 25 shows cross-sectional views of the applicator assembled according to several embodiments. [Figure 28F] Figure 25 shows cross-sectional views of the applicator assembled according to several embodiments. [Figure 28G] Figure 25 shows cross-sectional views of the applicator assembled according to several embodiments. [Figure 28H] Figure 25 shows perspective views of the applicator assembled according to several embodiments. [Figure 29] The following are exploded perspective views of applicators for skin sensor assemblies of analyte sensor systems according to several embodiments. [Figure 30] Figure 29 shows a cross-sectional view of a portion of the applicator according to several embodiments. [Figure 31] Cross-sectional views of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, are shown. [Figure 32A]An exploded perspective view of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, is shown. [Figure 32B] An exploded perspective view of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, is shown. [Figure 33A] Figure 32 shows sectioned perspective views of some feature parts of the applicator according to several embodiments. [Figure 33B] Figure 32 shows sectioned perspective views of some feature parts of the applicator according to several embodiments. [Figure 33C] Figure 32 shows sectioned perspective views of some feature parts of the applicator according to several embodiments. [Figure 33D] Figure 32 shows sectioned perspective views of some feature parts of the applicator according to several embodiments. [Figure 33E] Figure 32 shows sectioned perspective views of some feature parts of the applicator according to several embodiments. [Figure 34A] Cross-sectional views of the applicator shown in Figure 32 during operation are shown according to several embodiments. [Figure 34B] Several cross-sectional views of the applicator shown in Figure 32 in operation, according to some embodiments, are shown. [Figure 34C] Several cross-sectional views of the applicator shown in Figure 32 in operation, according to some embodiments, are shown. [Figure 34D] Several cross-sectional views of the applicator shown in Figure 32 in operation, according to some embodiments, are shown. [Figure 35A] Figure 32 shows cross-sectional views of the skin sensor assembly holding mechanism of the applicator according to several embodiments. [Figure 35B] Figure 32 shows cross-sectional views of the skin sensor assembly holding mechanism of the applicator according to several embodiments. [Figure 35C] Figure 32 shows cross-sectional views of the skin sensor assembly holding mechanism of the applicator according to several embodiments. [Figure 36A]Figure 32 shows a cross-sectional view of another skin-surface sensor assembly holding mechanism of the applicator according to several embodiments. [Figure 36B] Figure 32 shows a cross-sectional view of another skin-surface sensor assembly holding mechanism of the applicator according to several embodiments. [Figure 36C] Figure 32 shows a cross-sectional view of another skin-surface sensor assembly holding mechanism of the applicator according to several embodiments. [Figure 37A] Figure 32 shows a cross-sectional view of yet another skin-surface sensor assembly holding mechanism of the applicator according to several embodiments. [Figure 37B] Figure 32 shows a cross-sectional view of yet another skin-surface sensor assembly holding mechanism of the applicator according to several embodiments. [Figure 37C] Figure 32 shows a cross-sectional view of yet another skin-surface sensor assembly holding mechanism of the applicator according to several embodiments. [Figure 38] Figure 32 shows a perspective view of an applicator similar to that shown, which includes an operating element on the side of the housing, according to several embodiments. [Figure 39] Figure 38 shows a sectioned perspective view of a portion of the applicator according to several embodiments. [Figure 40A] Figure 32 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 40B] Figure 32 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 40C] Figure 32 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 40D] Figure 32 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 40E] Figure 32 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 40F] Figure 32 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 40G] Figure 32 shows perspective views of the steps for assembling the applicator according to several embodiments. [Figure 41A] The following are cross-sectional views of exemplary skin sensor assembly holding mechanisms for applicators of analyte sensor systems according to several embodiments. [Figure 41B] The following are cross-sectional views of exemplary skin sensor assembly holding mechanisms for applicators of analyte sensor systems according to several embodiments. [Figure 42A] A cross-sectional view of another exemplary skin sensor assembly holding mechanism for an analyte sensor system applicator is shown according to several embodiments. [Figure 42B] A cross-sectional view of another exemplary skin sensor assembly holding mechanism for an analyte sensor system applicator is shown according to several embodiments. [Figure 43A] A cross-sectional view of yet another exemplary skin sensor assembly holding mechanism for an analyte sensor system applicator is shown according to several embodiments. [Figure 43B] A cross-sectional view of yet another exemplary skin sensor assembly holding mechanism for an analyte sensor system applicator is shown according to several embodiments. [Figure 44] A perspective view of a portion of another exemplary skin sensor assembly holding mechanism of an applicator for an analyte sensor system, according to several embodiments, is shown. [Figure 45] A perspective view of a portion of an exemplary skin sensor assembly holding mechanism for an analyte sensor system applicator, according to several embodiments, is shown. [Figure 46] A perspective view of a portion of an exemplary skin sensor assembly holding mechanism for an analyte sensor system applicator, according to several embodiments, is shown. [Figure 47] Cross-sectional views of kinked needles for use in applicators of analyte sensor systems, according to several embodiments, are shown. [Figure 48A]Cross-sectional views of flared C-needles for use in applicators of analyte sensor systems, according to several embodiments, are shown. [Figure 48B] Plan views of flared C-needles for use in applicators of analyte sensor systems, according to several embodiments, are shown. [Figure 49] Perspective views of deflection tip needles for use in applicators of analyte sensor systems, according to several embodiments, are shown. [Figure 50] Perspective views of curved needles for use in applicators of analyte sensor systems, according to several embodiments, are shown. [Figure 51A] Cross-sectional views of the needle hub of the applicator of an analyte sensor system are shown according to several embodiments. [Figure 51B] Cross-sectional views of the needle hub of the applicator of an analyte sensor system are shown according to several embodiments. [Figure 52A] Cross-sectional views of injection cannulas incorporated into skin sensor assemblies of analyte sensor systems, according to several embodiments, are shown. [Figure 52B] Plan views of injection cannulas incorporated into skin sensor assemblies of analyte sensor systems according to several embodiments are shown. [Figure 53] Cross-sectional views of sensor holding mechanisms for applicators of analyte sensor systems, according to several embodiments, are shown. [Figure 54] A perspective view of another sensor holding mechanism for an applicator of an analyte sensor system, according to several embodiments, is shown. [Figure 55] A cross-sectional view of another sensor holding mechanism for an applicator of an analyte sensor system, according to several embodiments, is shown. [Figure 56A] A perspective view of another sensor holding element for an applicator of an analyte sensor system, according to several embodiments, is shown. [Figure 56B] A perspective view of another sensor holding element for an applicator of an analyte sensor system, according to several embodiments, is shown. [Figure 57]Cross-sectional views of yet another sensor holding element for an applicator of an analyte sensor system, according to several embodiments, are shown. [Figure 58] Cross-sectional views of yet another sensor holding element for an applicator of an analyte sensor system, according to several embodiments, are shown. [Figure 59A] Cross-sectional views of yet another sensor holding element for an applicator of an analyte sensor system, according to several embodiments, are shown. [Figure 59B] Cross-sectional views of yet another sensor holding element for an applicator of an analyte sensor system, according to several embodiments, are shown. [Figure 60] The images show cross-sectional views of skin-surface sensor assemblies having at least a portion of a sensor potted in a flexible material, according to several embodiments. [Figure 61] The diagrams show cross-sections of skin-mounted sensor assemblies, including open cavities configured to allow for a larger bending radius of the sensor, according to several embodiments. [Figure 62] The diagrams show cross-sections of skin-mounted sensor assemblies, including open cavities configured to allow for a larger bending radius of the sensor, according to several embodiments. [Figure 63] The diagrams show cross-sections of skin-mounted sensor assemblies, including open cavities configured to allow for a larger bending radius of the sensor, according to several embodiments. [Figure 64A] The battery engagement features of a skin-surface sensor assembly according to several embodiments are shown. [Figure 64B] The battery engagement features of a skin-surface sensor assembly according to several embodiments are shown. [Figure 65] A flowchart illustrating a method for applying a skin sensor assembly to the skin of a recipient, according to several embodiments, is shown. [Figure 66] The following illustrates the exemplary mechanisms of several feature parts of an applicator configured to apply a skin sensor assembly to the skin of a recipient, according to several embodiments. [Figure 67]Exemplary sterilization, packaging, and sealing features of applicators configured to apply a skin sensor assembly to the skin of a recipient are shown according to several embodiments. [Figure 68] The images show top perspective views of skin sensor assemblies according to several embodiments. [Figure 69] Figure 68 shows a bottom perspective view of a skin-surface sensor assembly according to several embodiments. [Figure 70] Figure 68 shows cross-sectional views of skin-surface sensor assemblies according to several embodiments. [Figure 71] This describes yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments. [Figure 72] Figure 71 shows exploded perspective views of the applicator according to several embodiments. [Figure 73A] The images show cross-sectional views of the applicators in operation, according to several embodiments, along the cutting line A-A' in Figure 71, as shown in Figures 71 and 72. [Figure 73B] The images show cross-sectional views of the applicators in operation, according to several embodiments, along the cutting line A-A' in Figure 71, as shown in Figures 71 and 72. [Figure 73C] The images show cross-sectional views of the applicators in operation, according to several embodiments, along the cutting line A-A' in Figure 71, as shown in Figures 71 and 72. [Figure 74A] Figures 71 and 72 show cross-sectional views of the applicators in operation along the cutting line B-B' in Figure 71, according to several embodiments. [Figure 74B] Figures 71 and 72 show cross-sectional views of the applicators in operation along the cutting line B-B' in Figure 71, according to several embodiments. [Figure 74C] Figures 71 and 72 show cross-sectional views of the applicators in operation along the cutting line B-B' in Figure 71, according to several embodiments. [Figure 75A] Figures 71 and 72 show enlarged views of some feature parts of the applicator according to several embodiments. [Figure 75B]Figures 71 and 72 show enlarged views of some feature parts of the applicator according to several embodiments. [Figure 76A] Figures 71 and 72 show enlarged views of some feature parts of the applicator according to several embodiments. [Figure 76B] Figures 71 and 72 show enlarged views of some feature parts of the applicator according to several embodiments. [Figure 77] Figures 71 and 72 show perspective partial sections of the needle carrier assembly, hub, and skin sensor assembly of the applicator according to several embodiments. [Figure 78] Figures 71 and 72 show cross-sectional views of the applicator hub and skin sensor assembly according to several embodiments. [Figure 79] Figures 71 and 72 show top views of a portion of the needle carrier assembly and hub according to several embodiments. [Figure 80A] The following are perspective views of the locking feature of a needle for use in an applicator of an analyte sensor system, according to several embodiments. [Figure 80B] The following are perspective views of the locking feature of a needle for use in an applicator of an analyte sensor system, according to several embodiments. [Figure 81A] Several cross-sectional views of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, as well as various feature parts and operating positions, are shown. [Figure 81B] Several cross-sectional views of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, as well as various feature parts and operating positions, are shown. [Figure 81C] Several cross-sectional views of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, as well as various feature parts and operating positions, are shown. [Figure 81D] Figures 81A to 81D show perspective views of various feature parts of the applicator according to several embodiments. [Figure 82A] Several cross-sectional views of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, as well as various feature parts and operating positions, are shown. [Figure 82B] Several cross-sectional views of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, as well as various feature parts and operating positions, are shown. [Figure 82C] Several cross-sectional views of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, as well as various feature parts and operating positions, are shown. [Figure 82D] Several cross-sectional views of yet another applicator for a skin sensor assembly of an analyte sensor system, according to several embodiments, as well as various feature parts and operating positions, are shown. [Figure 83] The images show cross-sectional views of applicators, including a deformable layer positioned above an operating element, according to several embodiments. [Figure 84] Perspective views of applicators utilizing a torsional actuation mechanism according to several embodiments are shown. [Figure 85] The images show cross-sectional views of applicators with an operating element mounted on the top, according to several embodiments. [Figure 86] The relationship between the axis, the insertion element, and the arc moved by the insertion element is shown in at least Figure 26C during insertion and retraction according to several embodiments. [Figure 87] Figures 3A, 3B, and 4 show cross-sectional views of skin sensor assemblies, further including an upper patch 328, according to several embodiments. [Figure 88A] The following are perspective views of another optional battery connection feature of a skin sensor assembly according to several embodiments. [Figure 88B] The following are perspective views of another optional battery connection feature of a skin sensor assembly according to several embodiments. [Figure 89]A flowchart of another method for applying a skin sensor assembly to the skin of a recipient, according to several embodiments, is shown. [Figure 90] Figures 71 and 72 show enlarged views of some feature parts of the applicator according to several embodiments. [Figure 91] Perspective views of skin-surface sensor assemblies according to several embodiments are shown. [Modes for carrying out the invention]

[0060] The following description and examples illustrate several exemplary embodiments. Those skilled in the art will recognize that there are many variations and modifications of the disclosure that are encompassed by their scope. Therefore, the description of certain exemplary embodiments should not be considered to limit the scope of the disclosure.

[0061] System Introduction Figure 1 shows an exemplary continuous analyte monitoring system 100, which includes an analyte sensor system 102, which includes a skin sensor assembly 160 configured to be fixed to the skin of an recipient via a base (not shown). In certain embodiments of this disclosure, the analyte sensor system 102 is operably connected to a recipient and a plurality of display devices 110-114. Exemplary display devices 110-114 may include computers such as smartphones, smartwatches, tablet computers, laptop computers, and desktop computers. In some embodiments, the display devices 110-114 may be Apple Watch, iPhone®, and iPad® manufactured by Apple Inc., or Windows or Google devices. Note that the display device 114 may, in lieu of or in addition to being a display device, be a drug delivery device capable of working with the analyte sensor system 102 to deliver drugs to the recipient. The analyte sensor system 102 may 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 communicate directly with one or more of the display devices 110-114 via wireless communication signals. As will be discussed in more detail below, the display devices 110-114 can also communicate with the analyte sensor system 102 between themselves and / or through each other. For ease of reference, wireless communication signals from the analyte sensor system 102 to the display devices 110-114 may be called “uplink” signals 128. For example, wireless communication signals from the display devices 110-114 to the analyte sensor system 102 may be called “downlink” signals 130. Wireless communication signals between two or more of the display devices 110-114 may be called “crosslink” signals 132.Furthermore, the wireless communication signal includes data transmitted by one or more of the display devices 110-113 via a “long-range” 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 long-range downlink signals 142 transmitted by the remote servers 190.

[0062] In the embodiment shown in Figure 1, one of the multiple display devices may be a custom display device 111 designed to display a particular type of displayable sensor information (e.g., numerical values ​​and arrows in some embodiments) related to analyte values ​​received from the sensor electronics module 126. In some embodiments, one of the multiple display devices may be a handheld device 112, such as a mobile phone or palmtop computer based on the Android®, iOS operating system, or other operating system, and the handheld device 112 may have a relatively large display and be configured to display a graphic representation of continuous sensor data (e.g., including current and historical data). Other display devices may include other handheld devices such as a tablet 113, a smartwatch 110, a drug delivery device 114, a blood glucose meter, and / or a desktop or laptop computer.

[0063] In the case of the display device 134e, which may be a drug delivery device in addition to a display device, it should be understood that the alerts and / or sensor information provided by the continuous analyte sensor 122 to the sensor electronics module 126 can be used to initiate and / or regulate drug delivery to the container 120.

[0064] During use, the sensing portion of the sensor 138 may be positioned beneath the skin of the recipient, and the contact portion of the sensor 138 can be electrically connected to the electronic unit 140. The electronic unit 140 can engage with a housing (e.g., a base) attached to an adhesive patch fixed to the skin of the recipient. In some embodiments, the electronic unit 140 is integrally formed with the housing. Furthermore, the electronic unit 140 may be disposable and directly bonded to the adhesive patch.

[0065] The continuous analyte sensor system 100 may include a sensor configuration that provides an output signal indicating the concentration of the analyte. The output signal, which includes sensor data (for example, raw data stream, filtered data, smoothed data, and / or otherwise transformed sensor data), is transmitted to a receiver.

[0066] In some embodiments, the analyte sensor system 100 includes a transdermal glucose sensor, such as that described in U.S. Patent Publication No. 2011 / 0027127A1, the entire contents of which are incorporated herein by reference. In some embodiments, the sensor system 100 includes a continuous glucose sensor and a transdermal sensor (for example, as described in U.S. Patent No. 6,565,509, as described in U.S. Patent No. 6,579,690, and / or U.S. Patent No. 6,484,046). The contents of U.S. Patent Nos. 6,565,509, 6,579,690, and 6,484,046 are incorporated herein by reference in their entirety.

[0067] Various signal processing techniques and embodiments of glucose monitoring systems suitable for use with the embodiments described herein are described in U.S. Patent Publication 2005 / 0203360A1 and U.S. Patent Publication 2009 / 0192745A1, which are incorporated herein by reference in their entirety. The sensor can be maintained above, in, or below the skin and / or can provide electrical connections of the sensor 138 to sensor electronics within the electronics unit 140, and can extend through a housing.

[0068] In some embodiments, the base, housing, wearable, and / or transmitter of the skin sensor assembly 160 may be interchangeable. In other embodiments, the base and housing of the skin sensor assembly 160 may differ in that they may be separate components from the sensor electronics module 140, for example, a transmitter or receiver.

[0069] In some embodiments, the sensor 138 is in the form of a wire. The distal end of the wire may be formed to have a conical shape, for example (to facilitate insertion of the wire into the recipient's tissue). The sensor 138 may include an elongated conductive core (e.g., a metal wire) or an elongated conductive body such as an elongated conductive core coated with one, two, three, four, five or more layers of material, each of which may or may not be conductive. The elongated sensor may be long and thin, but still flexible and strong. For example, in some embodiments, the minimum dimensions of the elongated conductive body are less than 0.1 inches, less than 0.075 inches, less than 0.05 inches, less than 0.025 inches, less than 0.01 inches, less than 0.004 inches, less than 0.002 inches, less than 0.001 inches, and / or less than 0.0005 inches.

[0070] The sensor 138 may have a circular cross-section. In some embodiments, the cross-section of the elongated conductive body may be oval, rectangular, triangular, polyhedron, 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 may be disposed on a substantially planar substrate. One or two additional conductive layers may be added to such electrodes (e.g., using an intervening insulating layer provided for electrical isolation). The conductive layers may consist of any suitable material. In certain embodiments, it may be desirable to use a conductive layer containing conductive particles (i.e., particles of conductive material) in a polymer or other binder.

[0071] In some embodiments, the material used to form the elongated conductive body (e.g., stainless steel, titanium, tantalum, platinum, platinum-iridium, iridium, certain polymers, and / or similar) can be strong and rigid, and therefore 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 may be greater than 58 kPsi and less than 2200 kPsi.

[0072] The electronic unit 140 can be detachably or permanently coupled to the sensor 138. The electronic unit 140 may include electronic circuits related to the measurement and processing of continuous analyte sensor data. The electronic unit 140 may be configured to execute algorithms related to the processing and calibration of sensor data. For example, the electronic unit 140 can provide various embodiments of the functionality of sensor electronics modules, such as those described in U.S. Patent Publication 2009 / 0240120A1 and U.S. Patent Publication 2012 / 0078071A1, the entire contents of which are incorporated herein by reference. The electronic unit 140 may include hardware, firmware, and / or software that enables the measurement of analyte levels via a glucose sensor, such as the analyte sensor 138.

[0073] For example, the electronic unit 140 may include a potentiostat, a power supply for supplying 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 unit 140 and one or more receivers, repeaters, and / or display devices such as devices 110-114. The electronic components may be fixed to a printed circuit board (PCB) or the like and can take various forms. The electronic components may take the form of integrated circuits (ICs), such as application-specific integrated circuits (ASICs), microcontrollers, and / or processors. The electronic unit 140 may also include sensor electronics configured to process sensor information, such as storing data, analyzing data flow, calibrating analyte sensor data, estimating analyte values, comparing estimated analyte values ​​with measured analyte values ​​corresponding to time, and analyzing fluctuations in estimated analyte values. Examples of systems and methods for processing sensor analyte data include U.S. Patent Nos. 7,310,544, 6,931,327, U.S. Patent Publication Nos. 2005 / 0043598A1, U.S. Patent Publication Nos. 2007 / 0032706A1, U.S. Patent Publication Nos. 2007 / 0016381A1, U.S. Patent Publication Nos. 2008 / 0033254A1, and U.S. Patent Publication Nos. 2005 / 0203 The details are described in U.S. Patent Publication No. 360A1, U.S. Patent Publication No. 2005 / 0154271A1, U.S. Patent Publication No. 2005 / 0192557A1, U.S. Patent Publication No. 2006 / 02225666A1, U.S. Patent Publication No. 2007 / 0203966A1, and U.S. Patent Publication No. 2007 / 0208245A1, the contents of which are incorporated herein by reference in their entirety. The electronic unit 140 can communicate with devices 110-114 and / or any number of additional devices via any preferred communication protocol.Examples of communication methods or protocols include radio frequencies; Bluetooth®; Universal Serial Bus; 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, including any wireless local area network (WLAN).

[0074] Additional sensor information is described in U.S. Patent Nos. 7,497,827 and 8,828,201. The entire contents of U.S. Patent Nos. 7,497,827 and 8,828,201 are incorporated herein by reference.

[0075] Any sensors shown or described herein may be analyte sensors, glucose sensors, and / or any other suitable sensors. Sensors described in the context of any embodiment may be any sensors described herein or incorporated by reference. Sensors shown or described herein may be configured to sense, measure, detect, and / or interact with any analyte.

[0076] As used herein, the term “analyte” is a broad term whose ordinary and customary meaning is evident to those skilled in the art (and not limited to any special or customized meaning), referring to, but not limited to, substances or chemical components in bodily fluids that can be analyzed (e.g., blood, interstitial fluid, cerebrospinal fluid, lymph, urine, sweat, saliva, etc.). Analytes may include naturally occurring substances, artificial substances, metabolites, or reaction products.

[0077] In some embodiments, the analyte for measurement by the sensing region, device, system, and method is glucose. However, other analytes are also conceivable, including ketone bodies, acetyl-CoA, acarboxyprothrombin, acylcarnitine, adenine phosphoribosyltransferase, adenosine deaminase, albumin, α-fetoprotein, amino acid profiles (arginine (Krebs cycle), histidine / urocanic acid, homocysteine, phenylalanine / tyrosine, tryptophan), andrenostenedione, antipyrine, arabinitol enantiomer, arginase, benzoylecgonine (cocaine), biotinidase, biopterin, c-reactive protein, Carnitine, carnosinase, CD4, ceruloplasmin, chenodeoxycholic acid, chloroquine, cholesterol, cholinesterase, cortisol, testosterone, choline, creatine kinase, creatine kinase MM isozyme, cyclosporine A, d-penicillamine, de-ethylchloroquine, dehydroepiandrosterone sulfate, DNA (acetylated polymorphism, alcohol dehydrogenase, α1-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, β-thalassemia, hepatitis B virus, HCMV, HIV-1, HTLV-1, Leber's hereditary optic neuropathy, MCAD, RNA, PKU, Plasmodium vivax, sex differentiation, 21-deoxycortisol), desbutylhalofantrin, dihydropteridine reductase, diphtheria / tetanus antitoxin, erythrocyte arginase, erythrocyte protoporphyrin, estella -ase D, fatty acids / acylglycine, triglycerides, glycerol, free β-human chorionic gonadotropin, free erythrocyte porphyrin, free thyroxine (FT4), free triiodothyronine (FT3), fumarylacetase, galactose / gal-1-phosphate, galactose-1-phosphate uridyltransferase, gentamicin, glucose-6-phosphate dehydrogenase, glutathione, glutathione peroxidase, glycocholic acid, glycosylated hemoglobin, halofantrine,Hemoglobin variants, hexosaminidase A, human erythrocyte carbonic anhydrase I, 17-α-hydroxyprogesterone, hypoxanthine phosphoribosyltransferase, immunoreactive trypsin, lactate, lead, lipoprotein ((a), B / A-1, β), lysozyme, mefloquine, netylmycin, phenobarbiton, phenytoin, phytanic acid / pristanic acid, progesterone, prolactin, prolidase, purine nucleoside phosphorylase, kinin, inverted triiodothyronine (rT3), selenium, serum pancreatic lipase, shisomecin, somatomedin C, specific antibodies (adenovirus, antinuclear antibody, anti-zeta antibody, arbovirus, Aujeszky's disease virus, dengue fever virus, guinea pig, tapeworm, Entamoeba histolytica, enterovirus, Giardia lamblia) Helicobacter pylori, Hepatitis B virus, Herpesvirus, HIV-1, IgE (atopic disease), Influenza virus, Donovan's leishmania, Leptospira, Measles / Mumps / Rubella, Mycoplasma leprae, Mycoplasma pneumoniae, Myoglobin, Irocystitis rotundifolia, Parainfluenza virus, Plasmodium falciparum, Poliovirus, Pseudomonas aeruginosa, Respiratory rash virus, Rickettsia (scrub typhus), Schistosomiasis mansoni, Toxoplasma gondii, Treponema pallidum, Trypanosoma cruz / Langer's, Vesicular stomatis virus Examples of substances that may be present include, but are not limited to, viruses (such as Bancroftian filarial parasites, 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.

[0078] Salts, sugars, proteins, fats, vitamins, and hormones that occur naturally in blood or interstitial fluid can also constitute analytes in certain embodiments. Analytes, such as metabolites, hormones, antigens, antibodies, etc., may be naturally present in body fluids or endogenous. Alternatively, analytes, such as contrast agents for imaging, radioisotopes, chemical agents, carbon fluoride-based artificial blood, or drugs or pharmaceutical compositions may be introduced into the body, including insulin, glucagon, ethanol, cannabis (marijuana, tetrahydrocannabinol, hashish), inhalants (nitrous oxide, amyl nitrite, butyl nitrite, chlorohydrocarbons, hydrocarbons), cocaine (crack cocaine), stimulants (amphetamine, methamphetamine, Ritalin, Cylert, Preludin, Didrex, PreState, Voranil, Sandrex, Plegine), and inhibitors (barbiturates, methacarone, tranquilizers, e.g., V Alium, Librium, Miltown, Serax, Equanil, Tranxene), hallucinogens (phencyclidine, lysergic acid, mescaline, peyote, psilocybin), narcotics (heroin, codeine, morphine, opium, meperidin, Percocet, Percodan, Tussionex, Fentanyl, Darvon, Talwin, Lomotil), designer drugs (fentanyl, meperidin, amphetamine, methamphetamine, and analogs of phencyclidine, e.g., Ecstasy), anabolic steroids, and nicotine can be introduced into the body or are exogenous. Metabolites of drugs and pharmaceutical compositions can also be considered as analytes. Analytes of neurochemicals and other chemicals produced in the body, such as 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 intermediates of the citric acid cycle can be analyzed.

[0079] Many embodiments described herein allow a base or housing, sensor module, transmitter or electronic unit, and / or sensor to be bonded to a recipient (e.g., to the recipient's skin) using an adhesive. The adhesive may be configured to adhere to the skin. The adhesive may include a pad (e.g., located between the adhesive and the base). Additional bonding information, including adhesive pad information, is described in U.S. Patent Application No. 14 / 835,603, filed on 25 August 2015. The entire contents of U.S. Patent Application No. 14 / 835,603 are incorporated herein by reference.

[0080] As described above, the system can be applied to the skin of a recipient. The skin sensor assembly may include a base containing an adhesive that attaches the glucose sensor to the skin. Other methods are possible, such as a strap or watch band.

[0081] Any feature described in the context of at least Figure 1 may be applicable to all aspects and embodiments specified herein. Furthermore, any feature of an embodiment can be combined in any way, partially or entirely, independently with other embodiments described herein, for example, one, two, or three or more embodiments may be combined in whole or partially. Furthermore, any feature of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be carried out by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system may be configured to carry out a method of another aspect or embodiment.

[0082] Throughout this disclosure, skin sensor assemblies, which may also be described as wearables, are referred to. Such skin sensor assemblies (see Figures 1–4 and 68–70) may be disposable or reusable, and may include a base or baseplate (see Figures 68–70) or not (see Figures 2–4). In some embodiments, a skin sensor assembly having a baseplate (e.g., Figures 68–70) may be reusable, while a skin sensor assembly without a baseplate (e.g., Figures 2–4) may be disposable. Figure 1 has already been discussed with respect to a skin sensor assembly 160, while Figures 2A–4 and 68–70 illustrate at least some other embodiments of skin sensor assemblies.

[0083] Figure 2A shows a perspective view of a skin sensor assembly 260 according to several embodiments. The skin sensor assembly 260 may comprise an outer housing including a first upper portion 292 and a second lower portion 294. In some embodiments, the outer housing may have a clamshell design. The skin sensor assembly 260 may include components similar to those of the electronic equipment unit 140 described above in Figure 1 (e.g., a potentiostat, a power supply for supplying power to the sensor 138, signal processing components, data storage components, and a communication module for unidirectional or bidirectional data communication (e.g., a telemetry module), a printed circuit board (PCB), an integrated circuit (IC), an application-specific integrated circuit (ASIC), a microcontroller, and / or a processor). The outer housing may feature a large round body with a tapered end on the opposite side of the large round body. The outer housing may further comprise an opening 296 disposed at the tapered end of the outer housing and adapted for the sensor 238 and needle insertion. The opening 296 may be an opening characterized by a U-shaped channel extending through the tapered end of the outer housing. The cutaneous sensor assembly 260 may further comprise an adhesive patch 226 configured to fix the cutaneous sensor assembly 260 to the skin of the recipient. As shown, the adhesive patch 226 may have an opening 298 having a similar shape to the opening 296 and substantially aligned with the opening 296. The sensor 238 may be configured to extend at least partially through the openings 296 and 298. In some embodiments, the adhesive patch 226 may include an adhesive suitable for skin adhesion, e.g., a pressure-sensitive adhesive (e.g., acrylic, rubber, or other preferred type) bonded to a carrier substrate for attachment to the skin (e.g., spunlace polyester, polyurethane film, or other preferred type), but any preferred type of adhesive is also conceivable.

[0084] The skin sensor assembly 260 may be attached to a recipient using an applicator adapted to provide a convenient and secure application. Such an applicator may also be used to insert the sensor 238 through the recipient's skin and / or to connect the sensor 238 to an electronic unit. Once the sensor 238 is inserted into the skin (and connected to the electronic unit), the sensor assembly can be detached from the applicator.

[0085] Figure 2B shows a bottom perspective view of the skin sensor assembly 260 of Figure 2A. Figure 2B shows openings 296 and 298 located on the side of the outer housing, which are fitted for the sensor 238 and needle insertion, respectively.

[0086] Figure 3A shows a perspective view of a skin sensor assembly 360 according to several embodiments. The skin sensor assembly 360 may comprise an outer housing including a first upper portion 392 and a second lower portion 394. In some embodiments, the outer housing may have a clamshell design. The skin sensor assembly 260 may include components similar to those of the electronic equipment unit 140 described in Figure 1 (e.g., a potentiostat, a power supply for supplying power to the sensor 138, signal processing components, data storage components, and a communication module for unidirectional or bidirectional data communication (e.g., a telemetry module), a printed circuit board (PCB), an integrated circuit (IC), an application-specific integrated circuit (ASIC), a microcontroller, and / or a processor). As shown, the outer housing may feature a substantially elliptical shape. The outer housing may further include a sensor assembly opening 396 that is arranged substantially through the central portion of the outer housing and is accommodating the sensor 338 and needle insertion via the bottom of the skin sensor assembly 360. In some embodiments, the sensor assembly opening 396 may be a channel or an elongated slot. The on-skin sensor assembly 360 may further comprise an adhesive patch 326 configured to fix the on-skin sensor assembly 360 to the recipient's skin. In some embodiments, the adhesive patch 326 may include an adhesive suitable for adhesion to the skin underneath, e.g., a pressure-sensitive adhesive (e.g., acrylic, rubber, or other preferred type) bonded to a carrier substrate for attachment to the skin (e.g., spunlace polyester, polyurethane film, or other preferred type), but any preferred type of adhesive is also conceivable. In some embodiments, the adhesive patch 326 may further include an adhesive on its upper side, e.g., the non-skin contact side, to help adhere the adhesive patch 326 to a portion of the applicator in question during manufacturing and / or to maintain the adhesive patch 326 in a substantially flat orientation before deployment to the recipient's skin. In some embodiments, the adhesive applied to the upper side may be weaker than the adhesive applied to the lower side to ensure proper transfer of the on-skin sensor assembly to the recipient's skin.As shown, the adhesive patch 396 may feature an opening 398 aligned with the sensor assembly opening 396 so that the sensor 338 can pass through the bottom of the on-skin sensor assembly 360 and the adhesive patch 396.

[0087] Figure 3B shows a bottom perspective view of the skin sensor assembly 360 shown in Figure 3A. Figure 3B further shows sensor assembly openings 396 and 398 located substantially in the central part of the bottom of the skin sensor assembly 360, both of which are fitted for the sensor 338 and needle insertion.

[0088] Figure 91 shows a perspective view of a skin sensor assembly 9160 according to several embodiments. The skin sensor assembly 9160 may be substantially similar to other skin sensor assemblies described in this application, such as skin sensor assemblies 160, 260, and 360. The skin sensor assembly 9160 may feature an adhesive patch 9126 and a clamshell design including an upper shell and a bottom shell, similar to the skin sensor assembly 360. Furthermore, the skin sensor assembly 9160 may include a plurality of mounting points 9162a and 9162b, similar to the skin sensor assembly 160. The skin sensor assembly 9160 may include an opening 9296. The opening 9296 may be a through-hole extending through the skin sensor assembly 9160. The opening 9296 may be configured to allow a needle and / or sensor to pass through. In some embodiments, the skin sensor assembly 9160 may further include an opening 9294. The opening 9294 can extend from the top surface of the skin sensor assembly 9150 through the skin sensor assembly 9160 to a certain depth. In some embodiments, the opening 9294 is configured to engage with an anti-rotation feature, such as the base 7152 of the needle hub 7150 shown in Figure 78.

[0089] In some embodiments, the skin sensor assembly 9160 includes an identification tag 9150. The identification tag 9150 may be located on the top surface of the skin sensor assembly 9150 (as shown in the figure) or on a side surface of the skin sensor assembly. The identification tag 9150 may be an image resembling a logo or mark that identifies the manufacturer of the skin sensor assembly. In addition, the identification tag 9150 may be configured to be scanned by a user in order to pair the skin sensor assembly with a device such as a handheld device 112. In some embodiments, the identification tag 9150 is a code, such as but not limited to a QR code®, a matrix code, a two-dimensional barcode, or a three-dimensional barcode. The code may be embedded in the image of the identification tag 9150.

[0090] Figure 4 shows a cross-sectional view of the skin sensor assembly 360 of Figures 3A and 3B. Figure 4 shows the first upper portion 392 and the second lower portion 394 of the outer housing, the adhesive patch 326, the sensor assembly opening 396 in the central portion of the skin sensor assembly 360, the opening 398 in the central portion of the adhesive patch 326, and the sensor 338 passing through the sensor assembly opening 396. The electronic equipment unit described above in relation to Figure 3A may further include a circuit board 404 and a battery 402 configured to supply power to at least the circuit board 404.

[0091] Figure 87 shows a cross-sectional view of the skin sensor assembly 360 of Figures 3A, 3B, and 4, further including an upper patch 328 according to several embodiments. The upper patch 328 may include on its underside an adhesive suitable for skin adhesion, device adhesion, or a combination thereof, such as a pressure-sensitive adhesive (e.g., acrylic, rubber, or other preferred type) bonded to a carrier substrate (e.g., spunlace polyester, polyurethane film, or other preferred type) for attachment to the skin, but any preferred type of adhesive is also conceivable. In some embodiments, such an adhesive may be the same as the adhesive applied to the underside of patch 326. In some other embodiments, the adhesive may be different from the adhesive applied to the underside of patch 326. In some embodiments, the upper patch 328 may be shaped as circular, elliptical, partial strip, X, or any other shape or form suitable for securing the upper patch 328 to the lower patch 326 and / or the recipient's skin. The upper patch 328 may completely or partially cover the skin sensor assembly 360. The upper patch 328 can improve the adhesive life of the on-skin sensor assembly 360 on the recipient's skin 130 by providing a single surface covering the wearable, which reduces the risk of accidental mechanical detachment (e.g., snagging, getting caught, tearing) by adding an additional adhesive contact area to the surface of the skin 130 and / or reducing the catch surface / edges on the on-skin sensor assembly 360. It is believed that snagging resistance can be improved by reducing the surface of the on-skin sensor assembly 360 which is substantially perpendicular to the body surface. Such an increased wearable life provided by the upper patch 328 can be a valuable characteristic, especially when the system moves toward and beyond a 10-14 day wearable adhesive solution.

[0092] In some embodiments, the upper patch 328 can be assembled to any applicator of this description on the skin sensor assembly 360, with its lower adhesive side exposed. When the skin sensor assembly 360 is deployed by the applicator, the patch 326 adheres to the recipient's skin 130, and the upper patch 328 may be adhered to the skin sensor assembly 360 and the recipient's skin 130 by one or more features of the applicator, for example, a holder and / or needle carrier assembly described in relation to any figure herein.

[0093] Applicator Embodiment Figure 5 shows exploded perspective views of an applicator 500 for applying a skin sensor assembly 160 to the skin 130 of a recipient, according to several embodiments. In some embodiments, the applicator 500 may include an applicator housing 502 having an opening at its bottom and configured to house at least one mechanism used for applying the skin sensor assembly 160 to the skin 130 of a recipient. The applicator housing 502 may be formed of any suitable material, such as polymer, polycarbonate, ABS, nylon, polyethylene, or polypropylene. In some embodiments, the applicator housing 502 may be configured to cover at least one feature portion of the applicator housing 502, such as a guide for a reciprocating or forward / backward mechanism (e.g., a Scotch yoke mechanism) (see Figure 6B).

[0094] The applicator 500 includes an actuation element 504 configured to actuate the drive assembly of the applicator 500. In some embodiments, the actuation element 504 may be a button, switch, toggle, slide, trigger, knob, rotating member, deformable and / or bendable component, or any other suitable mechanism for actinguating the drive assembly of the applicator 500.

[0095] The applicator 500 may further include a needle carrier assembly 508, which includes an insertion element (not shown in Figure 5) configured to insert at least partially into the skin 130 of a skin sensor assembly 160 (e.g., Figure 1). The insertion element is further shown in Figure 6H as being attached to the needle carrier assembly 508 and extending substantially distally along the insertion axis. In some embodiments, the needle carrier assembly 508 includes a needle carrier or shuttle. In some embodiments, the insertion element includes a needle, e.g., a single-opening needle, a deflected-tip needle with a deflected tip, a curved needle, a polymer-coated needle, a subcutaneous injection needle, or any other suitable type of needle or structure, as will be described in more detail in relation to Figures 47-50 and Figures 80A and 80B. In yet another embodiment, the insertion element may include the sensor 138 itself, which is rigid enough to be partially inserted into the recipient's skin 130 with minimal or no structural support, as described in U.S. Patent No. 9,357,951 filed September 29, 2010, U.S. Patent Publication No. 2014 / 0107450 filed February 28, 2013, and U.S. Patent Publication No. 2015 / 0289788 filed April 10, 2014. The entire contents of U.S. Patent No. 9,357,951, U.S. Patent Publication No. 2014 / 0107450, and U.S. Patent Publication No. 2015 / 0289788 are incorporated herein by reference.

[0096] The applicator 500 may further include a drive assembly 510 configured to drive the insertion element of the needle carrier assembly 508 distally to a distal insertion position and proximal from the distal insertion position to a proximal retraction position. The distal direction may be defined as extending toward the open end side of the applicator 500 along the path to which the needle carrier assembly 508 is configured to move. The distal direction may also be defined as the direction toward the user's skin. The proximal direction may be defined as the direction extending substantially opposite to the distal direction. In some embodiments, the distal and proximal directions extend along the insertion axis of the insertion element and the needle carrier assembly 508.

[0097] The drive assembly 510 may include a rotary drive element 514 coupled to the needle carrier assembly 508 via a shaft 526. In some embodiments, the rotary drive element 514 includes a cam-like feature having a substantially circular or oval outer circumference, such as a wheel cam. The rotary drive element 514 may be configured to rotate relative to the needle carrier assembly 508 about a rotation axis 518 that coincides with the centerline of the shaft 526. The rotary drive element 514 may further include a pin 516 disposed on the surface of the rotary drive element 514, radially displaced from the rotation axis 518. The pin 516 is configured to move within a guide in the applicator housing 502 (see Figure 6B).

[0098] The drive assembly 510 may further include a spring 512. The spring 512 may be a torsion spring, a clock spring, a power spring, or any other suitable type of spring. The spring 512 may be formed of any suitable material, including but not limited to plastic or metal, such as stainless steel. In some embodiments, the spring 512 is pre-compressed before the applicator is actuated. In some embodiments, the spring 512 is configured to be additionally loaded during the actuated applicator. The spring 512 may have a first end 520 coupled to the needle carrier assembly 508 and a second end 522 coupled to the rotary drive element 514. The spring 512 may be disposed coaxially with the shaft 526. The spring 512 may be configured to rotate the rotary drive element 514 in a unidirectional direction relative to the needle carrier assembly 508 when the drive assembly 510 is actuated. In some embodiments, the spring 512 is configured to unwind by rotating more than 0 degrees but less than 360 degrees when the drive assembly 510 is in operation. In some embodiments, the spring 512 is pre-wound between 30 degrees and 1440 degrees.

[0099] With respect to the needle carrier assembly 508, a rotary drive element 514 is configured to rotate around a rotating axis 518, and a pin 516 is constrained to move within a guide in the applicator housing 502. The rotational motion of the rotary drive element 514, driven by a spring 512, is converted into linear reciprocating motion of the needle carrier assembly 508, and therefore of the insertion element (not shown), along the axis 590. More specifically, the rotation of the rotary drive element 514 drives the insertion element 508 distally to the distal insertion position and proximal from the distal insertion position to the proximal retraction position. Such embodiments may eliminate the handoff mechanism between the drive assembly 510, which drives the needle carrier assembly 508 separately in the distal and proximal directions, by using a single mechanism to convert the rotational motion into reciprocating linear motion.

[0100] The applicator 500 may further include a holder 524 configured to be releasably coupled to the needle carrier assembly 508 and to guide the on-skin sensor assembly 160 while coupled to the needle carrier assembly 508. In some embodiments, the holder 524 may also be referred to as a carrier or transport member.

[0101] Figures 6A to 6H show cross-sectional and perspective views of some feature parts of the applicator 500 of Figure 5 according to several embodiments. Figure 6A shows a cross-sectional view of the applicator 500 including the applicator housing 502, the actuation element 504, the needle carrier assembly 508, the rotary drive element 514, the pin 516, and the holder 524. Each of these components may have at least the functionality described above in relation to Figure 5.

[0102] Figure 6B shows the guide 582 within the applicator housing 502. In some embodiments, the guide 582 may include a Scotch yoke track configured to move when the rotary drive element 514 rotates and the drive assembly 510 is actuated.

[0103] Figure 6C shows multiple tracks 622a, 622b, 622c within the applicator housing 502, on which one of each of the multiple projections or ribs 624a, 624b, 624c of the needle carrier assembly 508 slides. Thus, the tracks 622a-622c within the applicator housing 502 define the travel path of the needle carrier assembly 508. In some embodiments, this travel path is substantially linear and longitudinal. Although three tracks and projections are shown in Figure 6C, any number of tracks and each projection is conceivable. For ease of understanding, Figure 6C also shows a partial bottom view of the applicator 500, which also shows portions of the skin sensor assembly 160 and holder 524.

[0104] Figure 6D shows an embodiment in which the needle carrier assembly 508 includes a locking element 632 configured to prevent rotation of the rotary drive element 514. Specifically, the rotary drive element 514 includes a projection 634 that contacts the retaining element 632, which prevents the projection 634 from moving along a path that the spring 512 would otherwise take when releasing at least some of the energy stored in the rotary drive element 514. In some embodiments, the retaining element 632 includes a deflectable tab formed of a material such as polymer, polycarbonate, ABS, nylon, polyethylene, polypropylene, or any other suitable material. The actuating element 504 includes a projection 640 configured to deflect the retaining element 632 so that the projection 634 is no longer held by the retaining element 632, thereby allowing the rotary drive element 514 to rotate and actuating the drive assembly 510. The rotary drive element 514 further includes a ridge 636 configured to restrict the rotation of the rotary drive element 514 when the rotary drive element 514 rotates and the ridge 636 contacts the retaining element 632.

[0105] Figure 6E shows the retaining element 642 of the holder 524 and the stopping element 644 of the applicator housing 502, configured to fix the holder 524 to the applicator housing 502, when the needle carrier assembly 508 reaches the distal insertion position. In some embodiments, the retaining element 642 is a deflectable arm, or any other type of projection or snap. For example, as the needle carrier assembly 508 moves distally, the retaining element 642 slides along the inner surface of the applicator housing 502 until the retaining element 642 is slightly deflected by the stopping element 644 as a result of the spring 512 rotating the rotary drive element 514, and then snaps outward under the stopping element 644. At this point, as a result of the spring 512 further rotating the rotary drive element 514, the needle carrier assembly 508 can move freely in the proximal direction. The stopping element 644 would prevent the retaining element 642, and therefore the holder 524, from moving proximal. In this manner, after reaching the distal insertion position, the proximal movement of the needle carrier assembly 508 releases the holder 524 from the needle carrier assembly 508 and / or the skin sensor assembly 160.

[0106] Figure 6F shows a projection 652 of the holder 524 and a projection 654 of the applicator housing 502 configured to prevent the holder 524 from moving distally beyond the distal insertion position. For example, when the holder 524 is driven distally by the needle carrier assembly 508, the projection 652 moves along the inner surface of the applicator housing 502 until it contacts the projection 654, preventing the holder 524 from moving further distally at that point.

[0107] Figure 6G shows a surface sensor assembly 160 including a plurality of mounting points 662a–662f configured to mate with their respective retaining elements on the needle carrier assembly 508 and / or holder 524 while the applicator is moving distally toward at least partially distal insertion position during operation. In some embodiments, the mounting points 662a–662f are small grooves or recesses. Although a plurality of mounting points 662a–662f are shown, any number of mounting points are conceivable. In some embodiments, each retaining element may include a snap fit, friction fit, interference feature, elastomer grip, and / or adhesive configured to bond the surface sensor assembly 160 to the needle carrier assembly 508 and / or holder 524.

[0108] Furthermore, during pressure fluctuations, such as high altitude or vacuum during a sterilization process, air present within the skin sensor assembly 160 can exert deformable forces from within the cavity of the skin sensor assembly 160. Although not shown in Figure 6G, in some embodiments, the skin sensor assembly 160 may have portions formed of at least reduced thickness or a second material (e.g., elastomer), resulting in reduced strength and rigidity, and when the applicator 500 is subjected to such pressure fluctuations, the portions having reduced thickness or the second material deform in a controlled manner, thereby reducing or eliminating damage to the skin sensor assembly 160 that would otherwise occur due to undesirable, uncontrolled expansion of the skin sensor assembly 160. The portions formed of reduced thickness or the second material may be selected to keep controlled expansion away from data and / or retaining features that secure the skin sensor assembly to the applicator assembly. Such features may be present in any applicator described herein.

[0109] Figure 6H shows the retaining elements 672a and 672b of the holder 528, which are configured to releasably connect the supracutaneous sensor assembly 160 to the holder 528 when the needle carrier assembly 508 moves distally to the distal insertion position, and to detach the supracutaneous sensor assembly 160 from the holder 528 when the needle carrier assembly 508 moves proximal from the distal insertion position to the proximal retraction position. Specifically, the retaining elements 672a and 672b may each include first ends 676a and 676b, second ends 678a and 678b, and pivot points 680a and 680b. As the needle carrier assembly 508 moves distally to the distal insertion position, the first ends 676a, 676b of the retaining elements 672a, 672b are fixed within the respective guides 674a, 674b of the needle carrier assembly 508, and each of the retaining elements 672a, 672b is fixed to the interference points 682a, 682b of the needle carrier assembly 508, thereby releasably connecting the second ends 678a, 678b to the mounting points 662a, 662b of the surface sensor assembly 160. In some embodiments, the guides 674a, 674b include slots or stop elements. The retaining elements 642, 644 and / or projections 652, 654 are such that when the needle carrier assembly 508 is returned proximal, the needle carrier assembly 508 is separated from the holder 524 to fix the holder 524 in the distal insertion position (as shown in Figure 6E), thereby separating the first ends 676a, 676b of the retaining elements 672a, 672b from their respective slots 674a, 674b, and allowing the first ends 676a, 676b to deflect inward and the second ends 678a, 678b to deflect outward from the mounting points 662a, 662b of the surface sensor assembly 160 as the retaining elements 672a, 672b rotate around the pivot points 680a, 680b. Two retaining elements are shown, but any number of retaining elements are possible. Furthermore, several alternative mechanisms capable of performing such holding and releasing operations will be described in more detail, at least in relation to Figures 35A to 37C below. Any of these alternative mechanisms could be used with the applicator 500.

[0110] A brief description of the operation of the applicator 500 is given below with reference to Figures 7A to 8F, and several perspective views of the applicator in operation shown in Figure 5 are shown in order according to several embodiments.

[0111] Figure 7A shows the applicator 500 in its pre-operation state. The applicator housing 502 and slot 582 remain stationary relative to the recipient's skin during operation. The operating element 504 is in its pre-operation position. The insertion assembly 508 is also coupled in its pre-operation position to a holder 524 which is releasably coupled to the surface sensor assembly 160, as described at least in relation to Figures 6A–6H. At least a portion of the insertion element 674 of the needle carrier assembly 508 is positioned to protrude distally below the surface sensor assembly 160. The insertion element 674 may include a needle, e.g., a single-opening needle, a deflected-tip needle with a deflected tip, a curved needle, a polymer-coated needle, a subcutaneous injection needle with a deflected tip, or any other suitable type of needle or structure, as described at least in detail in relation to Figures 47–50 and 80A–80B. The insertion element 674 may be configured to guide at least a portion of the sensor 138 of the surface sensor assembly 160. The rotary drive element 514 of the drive assembly 510 is shown in the pre-operation position and has a pin 516 located in a first position within the guide 582 of the applicator housing 502 and a projection 634 that contacts the retaining element 632. In Figure 7A, the pin 516 is positioned at approximately 30 degrees (shown as clockwise, but counterclockwise is also possible) from the bottom dead center orientation with respect to the axis of rotation of the rotary drive element 514, which passes through the center of the plane on which the pin 516 is located.

[0112] Figure 7B shows the state of the applicator 500 during operation. The actuation element 504 is shown in the actuation position, for example, when pushed longitudinally distally by the user. In the actuation position, the actuation element 504 deflects the retaining element 632 so that the protrusion 634 of the rotary drive element 514 is not obstructed from moving, and thus allows the rotary drive element 514 to rotate by the unwinding of the spring 512. Since Figure 7B shows the applicator 500 during operation, the rotary drive element 514, pin 516, needle carrier assembly 508, insertion element 674, holder 524, and skin sensor assembly 160 are still shown in their pre-operation orientation and position, as in Figure 7A. However, the rotary drive element 514 rotates in the direction of the circular arrow, and the needle carrier assembly 508, insertion element 674, holder 524, and skin sensor assembly 160 are driven distally by the pin 516 under the rotation of the rotary drive element 514 to the distal insertion position. However, the disclosure is not limited in that way, and the rotational drive element 514 may be configured to rotate in the opposite direction to the direction of the circular arrow.

[0113] Figure 7C shows the state of the applicator 500 in operation. The actuation element 504 is shown in the actuation position in Figure 7B. The rotary drive element 514 is shown having rotated a portion of its pivot, indicated by the circular arrow, and the projection 634 has advanced beyond the retaining element 632. The pin 516 is shown having moved to a second position within the guide 582. This second position is shown to the left of the initial pre-actuation position. The insertion assembly 508, insertion element 674, holder 524, and skin sensor assembly 160 are driven distally toward the distal insertion position when the rotary drive element 514 is rotated by the force generated by the spring 512.

[0114] Figure 7D shows the applicator 500 in operation at the distal insertion position. The actuation element 504 is shown in the operating position in Figures 7B and 7C. The rotary drive element 514 is shown rotated further clockwise compared to Figure 7C, indicated by the circular arrow, and the projection 634 has advanced further beyond the retaining element 632. The pin 516 is shown moved to a third position within the guide 582, and is shown to the right of the first pre-actual position and the second operating position in Figure 7C. The insertion assembly 508, insertion element 674, holder 524, and skin sensor assembly 160 are driven distally to the distal insertion position as the rotary drive element 514 is further rotated by the force generated by the spring 512. At this distal insertion position, at least a portion of the insertion element 674 and at least a portion of the sensor 138 of the skin sensor assembly 160 can be inserted into the recipient's skin 130. In this position, the retaining elements 642 and 644 (see Figure 6) can engage, and the projections 652 and 654 (see Figure 6) can come into contact with each other. In Figure 7D, the pin 516 is positioned approximately 180 degrees (counterclockwise is also possible, but shown as clockwise) from the bottom dead center orientation with respect to the rotation axis of the rotary drive element 514.

[0115] Figure 7E shows the applicator 500 in operation. The actuation element 504 is shown in the operating position in Figures 7B–7D. The rotary drive element 514 is shown rotated further compared to Figure 7D and is indicated by a circular arrow. The pin 516 is shown moved to a fourth position within the guide 582. This fourth position is shown to the right of the first to third positions described above. The insertion assembly 508 and insertion element 674 are shown driven proximal from the distal insertion position when the rotary drive element 514 is further rotated by the force generated by the spring 512. The holder 524 and the skin sensor assembly 160 are shown separated from the needle carrier assembly 508 because the retaining elements 642, 644 (see Figure 6) are engaged and the projections 652 and 654 (see Figure 6) may be in contact with each other. In the position shown by Figure 7E, the skin sensor assembly 160 can also be separated from the holder 524, as described above in relation to Figure 6H.

[0116] Figure 7F shows the applicator 500 after activation. The actuation element 504 is shown in the actuation position in Figures 7B to 7E. The rotary drive element 514 is shown rotated further compared to Figure 7E, indicated by a circular arrow, with the ridge 636 in contact with the retaining element 632, thereby limiting further rotation of the rotary drive element 514. The pin 516 is shown having moved to the fifth position within the guide 582, and is shown to the left of the fourth right-end position as the pin 516 returns along the guide 582. The insertion assembly 508 and insertion element 674 are shown in the proximal retracted position. The holder 524 and the cutaneous sensor assembly 160 are shown separated from the needle carrier assembly 508. In the position shown by Figure 7F, the cutaneous sensor assembly 160 can also be separated from the holder 524, as previously mentioned in relation to Figure 6H. In Figure 7F, pin 516 is positioned approximately 330 degrees from the lower center orientation with respect to the rotation axis of the rotation drive element 514 (counterclockwise is also possible, but it is shown as clockwise).

[0117] Figures 8 to 10 show cross-sectional views of applicators 800, 900, and 1000, similar to applicator 500 in Figure 5, but instead have actuation elements 804, 904, and 1004 positioned on the upper, inner, and lower sides, respectively, rather than on the top of applicator housings 802, 902, and 1002. Applicators 800, 900, and 1000 may have substantially all the features of applicator 500 and may have substantially the same operation. For example, the applicator housings 802, 902, 1002, actuation elements 804, 904, 1004, needle carrier assemblies 808, 908, 1008, rotary drive elements 814, 914, 1014 including pins 816, 916, 1016 and protrusions 834, 934, 1034, and retaining elements 832, 932, 1032 of the applicator 500 may substantially correspond to the applicator housing 502, actuation element 504, needle carrier assembly 508, rotary drive element 514 including pins 516 and protrusions 504, and retaining element 502.

[0118] However, in Figure 8, the actuation element 804 may be positioned on the upper side rather than on the top of the applicator housing 802, and when actuated, the projection 834 may deflect the retaining element 832 so as not to rotate the rotary drive element 814 under the force of a spring (not shown in Figure 8), similar to the spring 512 of the applicator 500. In Figure 9, the actuation element 904 may be positioned on the inner side rather than on the top of the applicator housing 902, and when actuated, the projection 934 may deflect the retaining element 932 so as not to rotate the rotary drive element 914 under the force of a spring (not shown in Figure 9), similar to the spring 512 of the applicator 500. As shown, the inner position of the actuation element 904 may cause the retaining element 932 to be located substantially to the side of the rotary drive element 914.

[0119] In Figure 10, the actuation element 1004 is positioned on the underside rather than on the top of the applicator housing 1002, and when actuated, the projection 1034 may be configured to deflect the retaining element 1032 so that the rotary drive element 1014 is no longer rotated under the force of a spring (not shown in Figure 10), similar to the spring 512 of the applicator 500. As shown, the lower position of the actuation element 1004 may cause the retaining element 1032 to be positioned substantially to the side of the rotary drive element 1014, 50.

[0120] Next, we will describe examples of steps for assembling applicators such as applicators 500, 800, 900, and 1000 shown in Figures 5 and 8 to 10, in relation to Figures 11A to 11H.

[0121] Figure 11A shows the coupling of the first end 520 of the spring 512 to the needle carrier assembly 508. The first end 520 may be coupled to or disposed on a projection 1102 of the needle carrier assembly 508, and the spring 512 may be inserted around the hub 1104 of the needle carrier assembly 508 such that the spring 512 and the hub 1104 are arranged coaxially with each other.

[0122] Figure 11B shows the second end 522 of the spring 512 being coupled to the rotary drive element 514 and the shaft 526 being inserted into the hub 1104 of the needle carrier assembly 508, in which the shaft 526 can rotate internally. The shaft 526, hub 1104, and spring 512 may be arranged coaxially with respect to each other. As indicated by the circular arrow, the rotary drive element 514 rotates around the shaft 526 in a circular direction opposite to the direction in which the rotary drive element 514 rotates during operation, thereby allowing energy to be stored in the spring 512 in advance. The shaft 524 can be fully inserted into the portion of the needle carrier assembly 508 such that the projection 634 contacts the retaining element 632, thereby preventing it from rotating until the rotary drive element 514 is actuated. In some embodiments, the rotary drive element 514 can be rotated around the shaft 504 such that the spring 512 is only partially wound. In such embodiments, the spring 512 may be fully wound at a later stage of assembly. Figure 11B shows the rotary drive element 514 having a male configuration configured to mate with the female configuration of the hub 1104, but this disclosure also considers the rotary drive element 514 having a female configuration configured to mate with the male configuration of the hub 1104.

[0123] Figure 11C shows that the holder 524 is joined to the needle carrier assembly 508 by pushing the retaining elements 672a, 672b toward the center of the holder 524 and seating the first ends 676a, 676b of the retaining elements 672a, 672b in the respective slots 674a, 674b of the needle carrier assembly 508.

[0124] Figure 11D shows how the skin sensor assembly 160 is coupled to the holder 524 by snapping the second ends 678a, 678b (not shown in Figure 11D) of the retaining elements 672a, 672b to the mounting points 662a, 662b of the skin sensor assembly 160. In some embodiments, the retaining elements 672a, 672b may have snap-fit, friction-fit, interference-featured parts, elastomer grips, and / or adhesives.

[0125] Figure 11E shows the assembled needle carrier assembly 508, rotary drive element 514, holder 524, and skin sensor assembly 160 being inserted into the applicator housing 502 through the opening at the bottom of the applicator housing 502 and through the vertical portion of the guide 582 (see Figure 11F). During such insertion, the pin 516 of the rotary drive element 514 is inserted along at least the vertical portion of the guide 582 of the applicator housing 502, as shown in Figure 11F. Thus, the spring 512 (not shown in Figures 11E and 11F) may not be fully wound at this point, but rather partially wound to the extent that the pin 516 of the rotary drive element 514 is positioned to be inserted along the guide 582 of the applicator housing 502.

[0126] Figure 11G shows the assembled needle carrier assembly 508, rotary drive element 514, holder 524, and skin sensor assembly 160 being positioned further proximal within the applicator housing 502 so that the pin 516 of the rotary drive element 514 follows the guide 582 of the applicator housing 502, thereby fully rotating the rotary drive element 514 and fully winding the spring 512 (not shown in Figure 11G), positioning the projection 634 in contact with the retaining element 632 so that the drive assembly includes at least the rotary drive element 514 with the pin 516 and the spring 512 is loaded for operation.

[0127] Figure 11H shows an enlarged section of region 1106 in Figure 11G, illustrating the relationship between the rotary drive element 514, the pin 516, the guide 582, the projection 634, and the retaining element 632.

[0128] Figure 11J shows the insertion of the operating element 504 into the applicator housing 502.

[0129] Figure 12 shows an exploded perspective view of another applicator 1200 for applying a skin sensor assembly to the skin of a recipient, according to several embodiments. The applicator 1200 may include an applicator housing 1202 having an opening at its bottom and configured to house at least one mechanism used to apply the skin sensor assembly 160 to the skin of a recipient 130 (see Figure 2).

[0130] The applicator 1200 includes an actuation element 1204 configured to actuate the drive assembly of the applicator 1200. In some embodiments, the actuation element 1204 may be a button, switch, toggle, slide, trigger, knob, rotating member, deformable and / or bendable component, or any other suitable mechanism for actinguating the drive assembly of the applicator 1200. The applicator 1200 may further include a needle carrier assembly 1208, which includes an insertion element (not shown in Figure 12) configured to insert a sensor 138 of a skin sensor assembly 160 (e.g., Figure 1) into the skin 130 of the recipient. In some embodiments, the insertion element includes a needle, e.g., a C-needle, as will be described in more detail in relation to at least Figures 47-50 and 80A-80B.

[0131] The applicator 1200 may further include a drive assembly 1210 configured to drive the insertion element of the needle carrier assembly 1208 distally to a distal insertion position and proximal from the distal insertion position to a proximal retraction position. The distal direction may be defined as extending toward the open end side of the applicator 1200 along the path to which the needle carrier assembly 1208 is configured to move. The distal direction may also be defined as the direction toward the user's skin. The proximal direction may be defined as the direction extending substantially opposite to the distal direction. In some embodiments, the distal and proximal directions extend along the insertion axis of the insertion element and the needle carrier assembly 1208.

[0132] The drive assembly 1210 may include a spring 1212 having a first tongue 1220 (e.g., end) and a second tongue 1222 (e.g., end). The spring 1212 may be a torsion spring, a double torsion spring, or any other preferred type of spring. The spring 1212 may be supported by a spring spool 1250 including a first part 1250a and an optional second part 1250b. In some embodiments, the spring 1212 is self-supporting and not supported by a spring spool. The first part 1250a may be configured to couple with the second part 1250b such that the spring spool 1250 is arranged coaxially with the spring 1212 and supports the spring 1212 along its axis of rotation 1218. As shown in more detail in relation to Figure 13, the first tongue 1220 of the spring 1212 may be coupled to the applicator housing 1202, for example, to a hook or projection of the applicator housing 1202. The second tongue 1222 may be coupled to the needle carrier assembly 1208, such as to a hook or projection of the needle carrier assembly 1208. When the drive assembly 1210 is actuated, the first tongue 1220 and the second tongue 1222 of the spring 1212 are unwound in opposite clockwise or counterclockwise directions, thereby driving the spring 1212 in an arc and the insertion element 1208 distally to the distal insertion position and from the distal insertion position proximal. The arc on which the drive assembly 1210 moves may extend substantially perpendicular to the distal and proximal directions, or in an arc defined by the tongues of the spring and the point of rotation.

[0133] The applicator 1200 may further include a holder 1224 configured to be releasably coupled to the needle carrier assembly 1208 and to guide the on-skin sensor assembly 160 while coupled to the needle carrier assembly 1208. In some embodiments, the holder 1224 may include a stripper plate. Once the on-skin sensor assembly 160 is placed on the recipient's skin 130, as will be described in more detail below, the on-skin sensor assembly 160 can be peeled away from the holder 1224 and the needle carrier assembly 1208.

[0134] Figures 13A to 13F show perspective and section views of some features of the applicator 1200 of Figure 12 according to several embodiments. Figure 13A shows a section view of the applicator 1200, which includes an applicator housing 1202 having a retaining element 1334, an operating element 1204, a spring spool 1250, a spring 1212 having a first tongue 1220 and a second tongue 1222, a retaining element 1332, a holder 1224, and a needle carrier assembly 1208 having a skin sensor assembly 160. In some embodiments, the retaining element 1332 may include a snap fit, friction fit, interference feature, elastomer grip, and / or adhesive configured to connect the skin sensor assembly 160 to the needle carrier assembly 1208 and / or the holder 1224. Each of these components may have at least the functionality described above in relation to Figure 12. Furthermore, the first tongue 1220 is configured to rotate around the rotation point 1336 when the drive assembly is in operation. The second tongue 1222 is configured similarly.

[0135] Figure 13F shows an enlarged perspective view of the retaining element 1342 of the holder 1224 and the stop element 1344 of the applicator housing 1202, which are configured to secure the holder 1228 to the applicator housing 1202 when the needle carrier assembly 1208 reaches the distal insertion position. In some embodiments, the retaining element 1342 is a deflectable arm. For example, as the needle carrier assembly 1208 moves distally, the retaining element 1342 slides along the inner surface of the applicator housing 1202 as a result of the spring 1212 being partially unwound, and is deflected by the stop element 1344 until the retaining element 1342 snaps under the stop element 1344. In some embodiments, the functionality between the retaining element 1342 and the stop element 1344 may be interchangeable, for example, the stop element 1344 may be configured to be deflected and snapped by the retaining element 1342. At this point, the needle carrier assembly 1208 can move freely in the proximal direction, but as the spring 1212 is further unwound, the stopping element 1344 prevents the retaining element 1342, and therefore the holder 1224, from returning in the proximal direction. In this way, after reaching the distal insertion position, movement of the needle carrier assembly 1208 in the proximal direction allows the holder 1224 and / or the needle carrier assembly 1208 to be released from the surface sensor assembly 160.

[0136] Figure 13B shows an enlarged section of a portion of the needle carrier assembly 1208, including a retaining element 1332 configured to work in conjunction with a retaining element 1334 of the applicator housing 1202 to prevent the needle carrier assembly 1208 from separating from the applicator housing 1202 in a loaded pre-operation position. The actuating element 1204 is configured to deflect the retaining element 1334 so that the retaining element 1332 no longer retains the retaining element 1332, thereby allowing the spring 1212 to separate the needle carrier assembly 1208 from the applicator housing 1202 and actuate the drive assembly 1210.

[0137] Figure 13C shows an enlarged view of the second tongue 1222 of a spring coupled to the needle carrier assembly 1208, for example, via a hook 1348 configured to secure the second tongue 1222 to the needle carrier assembly 1208. The fastening concept described for the second tongue 1222 in Figure 13C can also be used for the first tongue 1220.

[0138] Figure 13D shows a skin sensor assembly 160 including a plurality of mounting points 662a–662c configured to mate with their respective retaining elements 1372a–1372c on the needle carrier assembly 1208 and / or holder 1224, while moving distally toward at least partially distal insertion position during applicator operation. In some embodiments, the holder 1224 may function similarly to a stripper plate in a punch and die manufacturing or injection molding process. Although a plurality of mounting points 662a–662c are shown, any number of mounting points are conceivable. In some embodiments, the retaining elements 1372a, 1372c may comprise snap-fit, friction-fit, interference features, elastomer grips, and / or adhesives.

[0139] The retaining elements 1372a to 1372c of the needle carrier assembly 1208 and / or holder 1224 are configured to releasably connect the supracutaneous sensor assembly 160 to the holder 1228 when the needle carrier assembly 1208 moves distally to the distal insertion position, and to detach the supracutaneous sensor assembly 160 from the needle carrier assembly 1208 and / or holder 1228 when the needle carrier assembly 1208 moves proximal from the distal insertion position to the proximal retraction position. Specifically, when the needle carrier assembly 1208 returns proximal, the retaining elements 1342 and 1344 fix the holder 1224 so that it does not move proximal at the distal insertion position. This separates the needle carrier assembly 1208 from the holder 1224 and the supracutaneous sensor assembly 160, thereby detaching the retaining elements 1372a to 1372c from the mounting points 662a to 662c of the supracutaneous sensor assembly 160. Although two holding elements are shown, any number of holding elements are conceivable. Furthermore, alternative mechanisms capable of performing such holding and releasing operations will be described further, at least in relation to Figures 35A to 37C below. Any of these alternative mechanisms are intended for use with applicator 1200.

[0140] Figure 13E shows a perspective view of multiple tracks 1322a, 1322b, and 1322c within an applicator housing 1202, each configured to slide over multiple projections 1324a, 1324b, and 1324c of the needle carrier assembly 1208. Thus, the tracks 1322a-1322c within the applicator housing 1202 define the travel path of the needle carrier assembly 1208. In some embodiments, this travel path is substantially linear and longitudinal. Although three tracks and projections are shown in Figure 13E, a single track or multiple tracks and their respective projections are also possible.

[0141] A brief description of the operation of applicator 1200 is given below with reference to Figures 14A to 14E, showing several cross-sectional views of the applicator in operation according to several embodiments.

[0142] Figure 14A shows the state of the applicator 1200 during operation. The actuation element 1204 is shown in the actuation position, for example, when pushed longitudinally distally by the user. In the actuation position, as the spring 1212 is unwound from its pre-wound state, the actuation element 1204 deflects the retaining element 1332 of the applicator housing 1202 so as not to hinder the movement of the needle carrier assembly 1208. Since Figure 14A shows the applicator 1200 during operation, the spring 1212, needle carrier assembly 1208, holder 1224, and skin sensor assembly 160 are shown in their pre-actuation orientation and position. However, the spring 1212 is partially unwound, and the needle carrier assembly 1208, holder 1224, and skin sensor assembly 160 are driven distally to the distal insertion position by such unwinding.

[0143] Figure 14B shows the state of the applicator 1200 in operation. The actuation element 1204 is shown in the actuation position in Figure 14A. The spring 1212 is partially unwound such that the first tongue 1220 is unwound in a first arc direction and the second tongue 1222 is unwound in a second arc direction opposite to the first arc direction. The spring 1212 moves in an arc direction substantially perpendicular to the distal and proximal directions, or in an arc defined by the tongues of the spring 1212 and their associated points of rotation. As a result, the needle carrier assembly 1208, insertion element 1374, holder 1224, and skin sensor assembly 160 are driven distally toward the distal insertion position by the force generated by the spring 1212.

[0144] Figure 14C shows the applicator 1200 in operation at the distal insertion position. The actuation element 1204 is shown in the operating position in Figures 14A and 14B. The spring 1212 is further unwound substantially in the direction of the horizontal arrow relative to its position as shown in Figures 14A and 14B. The insertion assembly 1208, the holder 1224, and the cutaneous sensor assembly 160 are driven distally to the distal insertion position by the force generated by the spring 1212. At this distal insertion position, at least a portion of the insertion element coupled to the needle carrier assembly 1208, and at least a portion of the sensor 138 of the cutaneous sensor assembly 160 (e.g., Figure 1), may be inserted into the recipient's skin 130, as shown in Figure 6 (not shown in Figures 14A-14E). Although not shown, at this position the retaining elements 1342, 1344 (see Figure 13) can engage with each other.

[0145] Figure 14D shows the applicator 1200 in operation. The actuation element 1204 is shown in the actuation position in Figures 14A–14C. The spring 1212 has been further unwound and moved substantially in the same direction as indicated by the arrow. If the unwinding of the spring 1212 in Figures 14A–14C caused distal movement of the needle carrier assembly 1208, further unwinding of the spring 1212 would result in movement of the needle carrier assembly 1208 to a proximal retracted position in the proximal direction, since the spring 1212 is on the opposite side of where the first tongue 1220 and the second tongue 1222 are fixed. The holder 1224 and the skin sensor assembly 160 are shown separated from the needle carrier assembly 1208 due to the engagement of the retaining element (see Figure 13). At the position shown in Figure 14D, the skin sensor assembly 160 can also be detached from the holder 1224, as previously mentioned in relation to the callout 1330 in Figure 13.

[0146] Figure 14E shows the applicator 1200 after activation. The actuation element 1204 is shown in the activated position in Figures 14A–14D. The spring 1212 is shown further unwound compared to the position shown in Figure 14D, and has moved substantially in the direction indicated by the arrow. The insertion assembly 1208 has moved to the proximal retracted position in the proximal direction indicated by the vertical arrow. The holder 1224 and the skin sensor assembly 160 are shown separated from the needle carrier assembly 1208.

[0147] Figures 15–17 show perspective views of several exemplary double torsion springs supporting different configurations of the applicator 1200 according to several embodiments. Thus, any of the springs described by Figures 15–17 may be used for the spring 1212 discussed earlier in relation to Figures 12–14E. As shown in Figures 15–17, cross bridges 1522c, 1622c, 1722c of springs 1512, 1612, 1712 may be provided by spreading one or more tongues in a particular direction.

[0148] For example, Figures 15 to 17 show double torsion springs 1512, 1612, and 1712, each comprising a first winding 1512a, 1612a, and 1712a and a second winding 1512b, 1612b, and 1712b. The double torsion springs 1512, 1612, and 1712 may be formed from a single segment of a suitable material, such as metal or plastic. The first windings 1512a, 1612a, and 1712a each include a first tongue 1520a, 1620a, and 1720a and a second tongue 1522a, 1622a, and 1722a. The second windings 1512b, 1612b, and 1712b each include the first tongues 1520b, 1620b, and 1720b and the second tongues 1522b, 1622b, and 1722b, respectively. For each spring 1512, 1612, and 1712, the second tongues 1522a, 1522b; 1622a, 1622b; 1722a, 1722b may be connected to one another by cross bridges 1522c, 1622c, and 1722c. The crossbridge 1522c in Figure 15 may have a length substantially equal to the distance 1530 between the first winding 1512a and the second winding 1512b, defined by the extensions of the second tongues 1522a and 1522b from the first winding 1512a and the second winding 1512b, respectively. The crossbridge 1622c in Figure 16 may have a length greater than the distance 1630 between the first winding 1612a and the second winding 1612b, defined by the extensions of the second tongues 1622a and 1622b from the first winding 1612a and the second winding 1612b, respectively, due to the second tongue 1622b of the second winding 1612b being flared toward the first tongue 1620b of the second winding 1612b.The crossbridge 1722c in Figure 17 has a length exceeding the distance 1730 between the first winding 1712a and the second winding 1712b, defined by the extensions of the second tongues 1722a, 1722b from the first winding 1712a and the second winding 1712b, respectively, due to the first tongue 1720a of the first winding 1712a and the second tongue 1722a of the second winding 1712b which is flared toward the first tongue 1720b of the second winding 1712b, and the second tongue 1722a of the first winding 1712a which is flared toward the second tongue 1722b of the second winding 1712b which is flared toward the first tongue 1720b of the second winding 1712b, and can provide a crossbridge 1722c with increased length compared to either the crossbridge 1522c shown in Figure 15 or the crossbridge 1622c shown in Figure 16.

[0149] Figures 18 to 23 show alternative drive assemblies for use with applicators such as the applicator 1200 in Figure 12, according to several embodiments. Figure 18 shows a drive assembly comprising a connecting element 1850. In some embodiments, the connecting element 1850 may include a bendable connecting portion. The bendable connecting portion may include one or more living hinges. In other embodiments, the connecting element 1850 may include at least two separate sections configured to pivot around a hinge that connects at least two separate sections.

[0150] A flex joint is a type of hinge assembly formed from an extension of a base material (e.g., polypropylene plastic). A hinge flex joint is a thin section of the parent material that acts as a bending connection between two larger sections of the parent material. Typically, the hinge, along with the larger sections of the parent material, is fabricated from a single continuous piece of parent material. Being relatively thin and typically made from flexible material, flex joints can rotate more than 180 degrees around a single axis, potentially over thousands or even millions of cycles. Unlike most hinges, which require multiple parts assembled in a conventional pivot mechanism, flex joints are not separate entities. They can be described as intentional tomographic lines at predetermined points in the material, designed to withstand repeated bending without breakage.

[0151] The connecting element 1850 has a first end 1852 connected to the applicator housing 1802, a second end 1854 connected to the needle carrier assembly 1808, and a hinge 1856 disposed between the first end 1852 and the second end 1854.

[0152] The drive assembly further comprises a spring 1812, which in some embodiments may be a single or double torsion spring. The spring 1812 includes a first tongue 1820 coupled to the applicator housing 1802 and / or the connecting element 1850 at a first end 1852 or at a position between the first end 1852 and the hinge 1856. The spring 1812 further includes a second tongue 1822 coupled to the needle carrier assembly 1808 and / or the connecting element 1850 at a second end 1854 or at a position between the second end 1854 and the hinge 1856. In some embodiments, the hinge 1856 may align with the axis of rotation 1818 of the spring 1812 to provide smooth operation and reduce stress caused by mismatched movement between the connecting element 1850 and the spring 1812.

[0153] The applicator 1200 utilizing the drive assembly 1810 may function substantially as described for the applicator 1200 in Figure 12, but may further include the first end 1852, the second end 1854 of the connecting element 150, and the hinge 1856 moving substantially in alignment with the first tongue 1820, the second tongue 1822, and the pivot axis 1818 of the spring 1812, respectively, during operation.

[0154] Figure 19 shows another drive assembly comprising a coupling element 1950. The coupling element 1950 has a first end 1952 coupled to the applicator housing 1902, a second end 1954 coupled to the needle carrier assembly 1908, and a hinge 1956 disposed between the first end 1952 and the second end 1954. The drive assembly further comprises a spring 1912, which in some embodiments may be a single or double torsion spring. The spring 1912 includes a first tongue 1920 coupled to the coupling element 1950 between the second end 1954 and the hinge 1956. The spring 1912 further includes a second tongue 1922 coupled to the needle carrier assembly 1908. When activated, the spring 1912 unwinds, causing the first tongue 1952 to arc, while the second tongue 1954 is held substantially stationary relative to the needle carrier assembly 1908. As the first tongue 1952 arcs, it drives the connecting element 1950 from its indicated bent position, causing the hinge 1956 to pivot until the connecting element 1950 is substantially vertical, and then continues to pivot until the connecting element 1950 is substantially mirror-image oriented from the orientation shown in Figure 19. This movement drives the needle carrier assembly 1908 distally, reaching the distal insertion position when the connecting element 1950 is substantially vertical, and then increasingly proximal as the connecting element 1950 is driven further from substantially vertical orientation to substantially mirror-image orientation relative to the orientation shown in Figure 19.

[0155] Figure 20 shows another drive assembly comprising a coupling element 2050. The coupling element 2050 has a first end 2052 coupled to the applicator housing 2002, a second end 2054 coupled to the needle carrier assembly 2008, and a hinge 2056 disposed between the first end 2052 and the second end 2054. The drive assembly further comprises a spring 2012, which in some embodiments may be a single or double torsion spring. The spring 2012 includes a first tongue 2020 coupled to the coupling element 2050 between the first end 2052 and the hinge 2056. The spring 2012 further includes a second tongue 2022 coupled to the applicator body 2002. When activated, the spring 2012 unwinds, causing the first tongue 2052 to arc, while the second tongue 2054 is held substantially stationary relative to the applicator body 2002. As the first tongue 2052 arcs, it drives the connecting element 2050 from its indicated bent position, causing the hinge 2056 to pivot until the connecting element 2050 is substantially vertical, and then continues to pivot until the connecting element 2050 is substantially mirror-image oriented from the orientation shown in Figure 20. This movement drives the needle carrier assembly 2008 distally, reaching the distal insertion position when the connecting element 2050 is substantially vertical, and then increasingly proximal as the connecting element 2050 is driven further from substantially vertical orientation to substantially mirror-image orientation relative to the orientation shown in Figure 20.

[0156] Figure 21 shows another drive assembly comprising a coupling element 2150. The coupling element 2150 has a first end 2152 coupled to the applicator housing 2102, a second end 2154 coupled to the needle carrier assembly 2108, and a hinge 2156 disposed between the first end 2152 and the second end 2154. The drive assembly further comprises a spring 2112, which in some embodiments may be a tension spring. A compression spring is also conceivable. However, a compression spring may be coupled between the hinge 2156 and the closer side of the applicator housing 2102. The spring 2112 includes a first end 2120 coupled to the coupling element 2150 and a second end 2122 coupled to the applicator body 2102. In some embodiments, the first end 2120 is coupled to the coupling element 2150 between the first end 2152 and the hinge 2156. In another embodiment, the first end 2120 is coupled to the connecting element 2150 by a hinge 2156. In yet another embodiment, the first end 2120 is coupled to the connecting element 2150 between the hinge 2156 and the second end 2154. When actuated, the spring 2112 unwinds through an arc extending in a substantially perpendicular direction to the distal and proximal directions, or from the indicated bending position, defined by the tongue of the spring and its respective point of rotation, driving the connecting element 2150, and the hinge 2156 pivots until the connecting element 2150 is substantially vertical, and then continues to pivot until the connecting element 2150 is substantially mirror-image oriented with respect to that shown in Figure 21. This movement drives the needle carrier assembly 2108 distally, reaching the distal insertion position when the connecting element 2150 is substantially vertical, and then increasingly proximal as the connecting element 2150 is further driven from a substantially vertical orientation to a substantially mirror-image orientation as shown in Figure 21.

[0157] Figure 22 shows another drive assembly comprising a leaf spring 2212. The leaf spring 2212 includes a first end 2220 coupled to the applicator housing 2202 and a second end 2222 coupled to the needle carrier assembly 2208. When actuated, the leaf spring 2212 is unloaded in a direction substantially parallel to the insertion axis, and when the leaf spring 2212 is unloaded, it drives the needle carrier assembly 2208 to the distal insertion position.

[0158] Figure 23 shows another drive assembly comprising a coupling element 2350. The drive assembly 2310 is substantially the same as the drive assembly 1910, except that the torsion spring 1912 is replaced with a leaf spring 2312. The coupling element 2350 has a first end 2352 coupled to the applicator housing 2302, a second end 2354 coupled to the needle carrier assembly 2308, and a hinge 2356 disposed between the first end 2352 and the second end 2354. The drive assembly further comprises a leaf spring 2312 having a first end 2320 coupled to the coupling element 2350 between the second end 2354 and the hinge 2356, and a second end 2322 coupled to the needle carrier assembly 2308. When activated, the spring 2312 is unloaded, causing the first end 2320 to arc, while the second end 2322 is held substantially stationary relative to the needle carrier assembly 2308. As the first tongue 2320 arcs, the first end 2320 drives the connecting element 2350 from the indicated bending position, and the hinge 2356 pivots until the connecting element 2350 is substantially vertical, and then continues to pivot until the connecting element 2350 is substantially mirror-image oriented from the one shown in Figure 23. This movement drives the needle carrier assembly 2308 distally, reaching the distal insertion position when the connecting element 2350 is substantially vertical, and then increasingly proximal as the connecting element 2350 is driven further from substantially vertical orientation to substantially mirror-image orientation relative to the one shown in Figure 23.

[0159] Next, an example of steps for assembling an applicator, such as the applicator 1200 in Figure 12, will be described in relation to Figures 24A to 24M. To the extent that any step is applicable, the assembly steps in Figures 24A to 24M can also be applied to any applicator that utilizes the drive assembly described in relation to Figures 18 to 23.

[0160] Figure 24A shows the first portion 1250a and the second portion 1250b of the spring spool 1250 being joined together inside the winding of the spring 1212. Figure 24B shows the assembled spring spool 1250 and spring 1212. The spring spool 1250 and spring 1212 are arranged coaxially with each other. Figure 24C shows the spring 1212 before winding in the direction indicated by the circular arrow, with the first tongue 1220 and the second tongue 1222 in the positions shown. Figure 24D shows the spring 1212 after winding, with the first tongue 1220 and the second tongue 1222 in the positions shown.

[0161] Figure 24E shows the coil spring 1212 being coupled to the needle carrier assembly 1208. In some embodiments, this includes coupling a first tongue 1220 to a hook 1348 of the needle carrier assembly 1208, and coupling a second tongue 1222 to the needle carrier assembly 1208 or arranging the second tongue 1222 toward it. Figure 24F shows a side view of the coil spring 1212 coupled to the needle carrier assembly 1208, while Figure 24G shows a perspective view of the arrangement shown in Figure 24F.

[0162] Figure 24H shows the holder 1224 being coupled to the needle carrier assembly 1208 and the skin sensor assembly 160 being coupled to the holder 1224. Figure 24J shows a side view of the assembled skin sensor assembly 160, holder 1224, and needle carrier assembly 1208, and Figure 24K shows a perspective view of the arrangement shown in Figure 24J.

[0163] Figure 24L shows the assembly of the complex, including the skin sensor assembly 160, holder 1224, needle carrier assembly 1208, and spring 1212, into the applicator housing 1202 through the opening at the bottom of the applicator housing 1202, and the insertion of the actuation element 1204 into the applicator housing 1202. Figure 24M shows the result of the assembly shown in Figure 24L.

[0164] Figure 25 shows an exploded perspective view of yet another applicator 2500 for a skin sensor assembly 160 of an analyte sensor system, according to several embodiments. The applicator 2500 may include an applicator housing 2502 configured to house one or more mechanisms for applying the skin sensor assembly 160 to the skin 130 of a recipient. The applicator housing 2502 may be formed of any suitable material, such as polymer, polycarbonate, ABS, nylon, polyethylene, or polypropylene.

[0165] The applicator 2500 includes an actuation element 2504 configured to actuate the drive assembly of the applicator 2500. In some embodiments, the actuation element 2504 may be a button, switch, toggle, slide, trigger, knob, rotating member, deformable and / or bendable component, or any other suitable mechanism for actinguating the drive assembly of the applicator 2500. The applicator 2500 may further include a needle carrier assembly 2508, which includes an insertion element 2574 configured to insert a sensor 138 (e.g., Figure 1) of a cutaneous sensor assembly 160 (e.g., Figure 1) into the skin 130 (e.g., Figure 1) of the recipient. In some embodiments, the insertion element 2574 includes a needle, e.g., a single-opening needle, a needle with a deflected tip, a curved needle, a polymer-coated needle, a subcutaneous injection needle, or any other suitable type of needle or structure, as will be described in more detail in relation to at least Figures 47-50 and Figures 80A-80B. In yet another embodiment, the insertion element may include a sensor 138 that is rigid enough to be partially inserted into the recipient's skin 130 with minimal or no structural support.

[0166] The applicator 2500 can further include a drive assembly 2510 configured to drive the insertion element 2574 of the needle carrier assembly 2508 in a distal direction to a distal insertion position and in a proximal direction from the distal insertion position to a proximal retracted position.

[0167] The applicator 2500 can further include a holder 2524 releasably coupled to the needle carrier assembly 2508 and configured to guide the on-skin sensor assembly 160 while coupled to the needle carrier assembly 2508. As will be described in more detail below, when the on-skin sensor assembly 160 is disposed on the skin 130 of the recipient, the on-skin sensor assembly 160 can be detached from the holder 2524 and the needle carrier assembly 2508.

[0168] The drive assembly 2510 can include a spring 2512 that can be any suitable type of spring, such as a compression spring, a tension spring, a leaf spring, a flexure arm spring, etc. The spring 2512 includes a first end 2520 coupled to the applicator housing 2502 and a second end coupled to the needle carrier assembly 2508. The spring 2520 can be configured to drive the needle carrier assembly 2508 in a distal direction during operation of the drive assembly 2510. In some embodiments, the spring 2512 can be pre-loaded, for example, at the factory. In some other embodiments, the spring 2512 can be loaded by an action of a user of the applicator 2500.

[0169] The drive assembly 2510 further includes a spring 2528 that can be coupled to the applicator base 2530 of the applicator 2500. In some embodiments, the spring 2528 may be a compression spring, a tension spring, a leaf spring, a flexure arm spring, or the like. In some embodiments, the spring 2528 may be pre-loaded, for example, at the factory. In some other embodiments, the spring 2528 may be loaded by the user's operation. In still other embodiments, the spring 2528 can be loaded by unloading the spring 2512. The spring 2528 may include one or more portions configured to drive the needle carrier assembly 2508 in a proximal direction from a distal insertion position, as will be described in more detail below.

[0170] Figures 26A - 26D show cross-sectional and bottom views of some features of the applicator 2500 of FIG. 25 according to some embodiments. FIG. 26A shows a perspective cutaway view of the applicator 2500 including the applicator housing 2502, the actuating element 2504, the applicator base 2530 including the protrusion 2602, the spring 2512, the leaf spring(s) 2528, the needle carrier assembly 2508, the holder 2524, and the on-skin sensor assembly 160. Each of these components may have the functionality described above at least in relation to FIG. 25.

[0171] Figure 26B shows perspective views of some features of the holder 2524, the applicator base 2530, and the actuation element 2504. The spring 2512 is configured to be coupled at a first end to the applicator housing 2502 and at a second end to the holder 2524. In the pre-actuation state, the spring 2512 may be configured to store energy for driving the holder 2512 (and the needle carrier assembly 2508) distally to the distal insertion position when actuated. The holder 2524 includes a shaft 2614 configured to snap to the applicator base 2530 such that the holder 2524 is configured to pivot substantially in an arc around the shaft 2614. In Figure 26B, the actuation element 2504 is shown to include a projection 2612 configured to guide the holder 2524 to a shown pre-actuation position until the actuation element 2504 is actuated, thereby displacing the projection 2512 from its pre-actuation direction relative to the holder 2524 and releasing the holder 2524. Figure 26B further shows that the leaf spring(s) 2528 are not coupled to the holder 2524. Instead, the leaf spring(s) 2528 are coupled to the needle carrier assembly 2508 and configured to drive the needle carrier assembly 2508 from the distal insertion position to the proximal position. Although the actuation element 2504 is shown as a button, the disclosure further envisions the actuation element 2504 as any other suitable mechanism for acting a switch, toggle, slide, trigger, knob, rotating member, deformable and / or bendable component, or drive assembly of the applicator 2500. Furthermore, although the actuation element 2504 is shown to be disposed on the side of the applicator housing 2502, the disclosure intends any other position, for example, on the top, bottom, or other side position of the applicator housing 2502, and / or any other positioning angle relative to the applicator housing 2502.

[0172] Figure 26C shows an exploded perspective view of the needle carrier assembly 2508, the insertion element 2674, and the holder 2524. The insertion element 2674 is coupled to the needle carrier assembly 2508. In some embodiments, the insertion element 2674 includes a single-opening needle configured to guide and insert the sensor 138 of a skin sensor assembly 160 (e.g., Figure 1) into the skin 130 of the recipient. The insertion assembly 2508 is coupled at a first end to the shaft 2614 of the holder 2524. The insertion assembly 2508 further comprises a retaining element 2622 configured to releasably couple the second end of the needle carrier assembly 2508 to the holder 2524. The insertion assembly 2508 further comprises a retaining element 2604 configured to releasably couple the skin sensor assembly 160 to the needle carrier assembly 2508 and the holder 2524. In some embodiments, the retaining element 2604 may include a snap fit, friction fit, interference feature, elastomer grip, and / or adhesive configured to connect the skin sensor assembly 160 to the needle carrier assembly 2508 and / or holder 2524. The spring 2512 is configured to drive the needle carrier assembly 2508 and holder 2524 distally along an arc defined by the axis 2614 to the distal insertion position when the applicator 2500 is actuated. When the needle carrier assembly 2508 is driven distally along the arc, the spring 2512 transmits at least a portion of its stored energy to the leaf spring(s) 2528. In some other embodiments, the leaf spring(s) 2528 can be preloaded so that the spring 2512 does not transmit stored energy to the leaf spring(s) 2528. When the needle carrier assembly 2508 is driven distally, the projection 2602 of the applicator base 2530 is configured to sufficiently deflect the retaining element 2622, separating the needle carrier assembly 2508 from the holder 2524 at a substantially distal insertion position, thereby detaching the second end of the needle carrier assembly 2508 from the holder 2524.Therefore, from the distal insertion position, the currently loaded leaf spring(s) 2528 is configured to drive the needle carrier assembly 2508 proximal in the arc from the distal insertion position to the proximal retraction direction.

[0173] Figure 26D shows a portion 2632 of the actuator element 2504 that is coupled to the applicator housing 2502 and configured to act as a return spring, returning the actuator element 2504 to its pre-actuated position after actuation. For example, when the actuator element 2504 is pushed to the right as shown in Figure 26D, portion 2632 deforms relative to the applicator housing 2502, thereby effectively acting as a spring and returning the actuator element 2504 to its pre-actuated position when unloaded.

[0174] Figures 27A to 27E show several cross-sectional views of the applicator 2500 of Figure 25 in operation, according to several embodiments. Figure 86 shows the relationship between the shaft 2614, the insertion element 2674, and the arc 8602 moved by the insertion element 2674 during insertion and retraction, according to several embodiments. Figure 27A shows the applicator 2500 in operation. For example, the actuation element 2504 is shown in the actuation position, for example, pushed inward, thereby releasing the holder 2524 from its fixed pre-actuation state. The spring 2512, needle carrier assembly 2508, insertion element 2674, holder 2524, and skin sensor assembly 160 are all shown in their pre-actuation positions.

[0175] Figure 27B shows the applicator 2500 in operation. The spring 2512 drives the holder 2524, and thus releasely connects the needle carrier assembly 2508, the insertion element 2674, and the skin sensor assembly 160 distally along the arc 8602 (see Figure 86) defined by the axis 2614. In some embodiments, the radius 8604 (see Figure 86) of the arc 8602 may be between 20 millimeters (mm) and 80 mm, although larger or smaller radii than this range are also possible.

[0176] With respect to Figure 86, the radius 8604 of this arc 8602 may depend on one or more of the following: the distance 8606 from the recipient's skin 130 to the axis 2614, the height 8608 of the on-skin sensor assembly 160 from the bottom opening or surface of the applicator 2500 or from the axis 2614, and / or the position of the sensor 138 within the on-skin sensor assembly 160. The selection of the radius 8604 may be made, at least in part, to minimize tissue trauma, optimize the deployment of the sensor 138, and minimize insertion and / or retraction friction between the insertor and the recipient's tissue.

[0177] For example, with respect to Figures 27A and 86, the angle 2710 between the needle axis and the bottom surface of the on-skin sensor assembly can be calculated so that the minimum offset between the straight needle path and the ideal curved profile 8602 is achieved. In some embodiments, an angle of approximately 71 degrees between the needle axis and the bottom surface of the on-skin sensor assembly was determined to result in less lateral movement of the tip of the insertion element 2674 in the recipient's skin compared to an angle of approximately 90 degrees between the needle axis and the bottom surface of the on-skin sensor assembly. However, this angle may depend on at least some of the same factors that influence the ideal radius of the arc.

[0178] Furthermore, as will be described in more detail in relation to at least Figures 47-50 and Figures 80A-80B, a variety of needle shapes can be utilized, including, but not limited to, straight needle shapes, kinked needle shapes (e.g., two or more substantially straight sections with one or more bent sections interposed between them), and fully or partially curved needle shapes (e.g., a curved distal section configured to at least partially penetrate the recipient's skin with or without a straight proximal section).

[0179] Figure 27C shows the applicator 2500 in the distal insertion position. The spring 2512 has a drive holder 2524, and thus the needle carrier assembly 2508, insertion element 2674, and skin sensor assembly 160 are coupled in a manner that allows them to be released to the distal insertion position in the distal direction. In addition, the projection 2602 of the applicator base 2530 deflects the retaining arm 2622 sufficiently to release the second end of the needle carrier assembly 2508 from the holder 2524 in preparation for movement from the distal insertion position in the proximal direction.

[0180] Figure 27D shows the applicator 2500 in the retraction position. The spring 2512 remains unloaded, pinning the holder 2524 to the distal insertion position. However, the leaf spring(s) 2528, which is still in contact with the now-released needle carrier assembly 2508, drives the needle carrier assembly 2508 and the coupled insertion element 2674 proximal from the distal insertion position to the proximal retraction position. The retaining element(s) 2604 is released at the distal insertion position from the spring 2512 that pins the holder 2524, and therefore from the cutaneous sensor assembly 160 disposed beneath it. In some embodiments, the retaining element(s) 2604 may include a snap fit, a friction fit, an interference feature, an elastomer grip, and / or adhesive.

[0181] Figure 27E shows the applicator 2500 in the proximal retracted position. A leaf spring 2528 drives the needle carrier assembly 2508 and insertion element 2674 in the proximal direction to the proximal retracted position. The applicator 2500 can then be released from the recipient's skin, thereby removing all parts of the applicator 2500 from the recipient's skin except for the on-skin sensor assembly 160 and sensor 138 (e.g., Figure 1), which are now at least partially inserted into the recipient's skin.

[0182] Figures 28A–28H show steps for assembling the applicator 2500 of Figure 25 according to several embodiments. Figure 28A shows the step of coupling the insertion element 2674 to the needle carrier assembly 2508. In some embodiments, the insertion element 2674 may be coupled to the needle carrier assembly 2508 at an angle substantially consistent with the circular path insertion element 2674, so that the needle carrier assembly 2508 traverses during operation. Figure 28B shows the step of coupling the holder 2524 to the needle carrier assembly 2508 by coupling the needle carrier assembly 2508 to the axis 2614 of the holder 2524 and the retaining element 2622 to the holder 2524. Figure 28C shows the step of coupling the skin sensor assembly 160 to the holder 2524 and the needle carrier assembly 2508 by engaging the retaining element 2604 of the needle carrier assembly 25089 with the skin sensor assembly 160.

[0183] Figure 28D shows the step of inserting the actuation element 2504 into the applicator housing 2502. Figure 28E shows the step of connecting the first end of the spring 2512 to the applicator housing 2502 through an opening at the bottom of the applicator housing 2502. Figure 28F shows the step of inserting the assembly 2800c resulting from the step(s) shown in Figure 28C into the applicator housing 2502. In the assembly 2800c shown in Figure 28F, the spring 2512 is positioned to contact the holder 2524, which is secured by the projection 2612 of the actuation element 2504.

[0184] Figure 28G shows the step of coupling the applicator base 2530 to the applicator housing 2502. The shaft 2614 of the holder 2524 is coupled to the applicator base 2530, and the leaf spring(s) 2528 are positioned to contact the needle carrier assembly 2508. Figure 28H shows the applicator 2500 in its assembled form. In this step, the applicator base 2530 may be coupled to the applicator housing 2502 by, for example, ultrasonic welding, press fitting, snap fitting, adhesive, or any other preferred method of fixing plastic materials together.

[0185] Figure 29 shows an exploded perspective view of yet another applicator 2900 for applying a skin sensor assembly to the skin 130 of a recipient, according to several embodiments. The applicator 2900 may include an applicator housing 2902 having an opening at its bottom and configured to house at least one mechanism used for applying the skin sensor assembly 160 to the skin 130 of a recipient.

[0186] The applicator 2900 includes an actuation element 2904 configured to actuate the drive assembly of the applicator 2900. In some embodiments, the actuation element 2904 may be a button, switch, toggle, slide, trigger, knob, rotating member, deformable and / or bendable component, or any other suitable mechanism for actinguating the drive assembly of the applicator 2900. The applicator 2900 may further include a needle carrier assembly 2908, which includes an insertion element (see Figure 30) configured to insert a sensor 138 of a cutaneous sensor assembly 160 (e.g., Figure 1) into the skin 130 of the recipient. In some embodiments, the insertion element includes a needle, e.g., a single-opening needle, a needle with a deflected tip, a curved needle, a polymer-coated needle, a subcutaneous injection needle, or any other suitable type of needle or structure, as will be described in more detail in relation to at least Figures 47-50 and Figures 80A-80B. In yet another embodiment, the insertion element may comprise a sensor 138 itself that is rigid enough to be partially inserted into the recipient's skin 130 with minimal or no structural support.

[0187] The applicator 2900 may further comprise a drive assembly 2910 configured to drive the insertion element of the needle carrier assembly 2908 distally to a distal insertion position and proximal from the distal insertion position to a proximal retraction position. The distal direction may be defined as extending toward the open end side of the applicator 2900 along the path to which the needle carrier assembly 2908 is configured to move. The distal direction may also be defined as the direction toward the user's skin. The proximal direction may be defined as the direction extending substantially opposite to the distal direction. In some embodiments, the distal and proximal directions extend along the insertion axis of the insertion element and the needle carrier assembly 2908.

[0188] The drive assembly 2910 may include a rotary drive element 2914 disposed within the needle carrier assembly 2908 and configured to rotate relative to the needle carrier assembly 2908 about a pivot axis 2918 parallel to the centerline of the needle carrier assembly 2908. In some embodiments, the rotary drive element 2914 is configured to rotate in a plane substantially perpendicular to the proximal and distal directions. In some embodiments, the rotary drive element 2914 may include a barrel cam. The rotary drive element 2914 includes a ridge 2916 that defines a variable cam path around at least a portion of the circumference of the rotary drive element. The ridge 2916 is configured to slide along a channel on the inner surface of the needle carrier assembly 2908 (see Figure 30) as the rotary drive element 2914 rotates, thereby driving the needle carrier assembly 2908 distally to the distal insertion position and then proximal to the proximal retraction position defined by the variable cam path of the ridge 2916.

[0189] The drive assembly 2910 may further include a spring 2912 disposed within the rotary drive element 2914. The spring 2912 may be a torsion spring or any preferred type of spring. The spring 2912 may have a first end 2920 coupled to the applicator housing 2902 and a second end 2922 coupled to the rotary drive element 2914. The spring 2912 may be disposed coaxially with the rotary drive element 2914 and the needle carrier assembly 2908. The spring 2920 may be configured to rotate the rotary drive element 2914 in a unidirectional direction relative to the needle carrier assembly 2908 when the drive assembly 2910 is operated.

[0190] For the needle carrier assembly 2908, a rotational drive element 2914 configured to rotate about the axis of rotation 2918, and a ridge 2916 constrained to move within a channel of the needle carrier assembly 2908, the rotational movement of the rotational drive element 2914 caused by the spring 2912 is converted into a linear reciprocating movement of the needle carrier assembly 2908, and thus of the insertion element (see FIG. 30). More specifically, the rotation of the rotational drive element 2914 drives the insertion element 2908 in the distal direction to the distal insertion position and in the proximal direction from the distal insertion position to the proximal retracted position.

[0191] The applicator 2900 can be releasably coupled to the needle carrier assembly 2908 via a retaining element(s) 2980, and further include a holder 2924 configured to guide the on-skin sensor assembly 160 while coupled to the needle carrier assembly 2908. In some embodiments, the retaining element(s) 2980 can include snap fits, friction fits, interference features, elastomeric grips, and / or adhesives configured to couple the on-skin sensor assembly 160 to the needle carrier assembly 2908 and / or the holder 2924. When the on-skin sensor assembly 160 is disposed on the recipient's skin 130, the on-skin sensor assembly 160 can be detached from the holder 2924 and the needle carrier assembly 2908.

[0192] FIG. 30 shows a perspective cutaway view of a portion of the applicator 2900 of FIG. 29, according to some embodiments. FIG. 30 shows at least one protrusion 3024 of the needle carrier assembly 2908 configured to slide within a track (not shown in FIG. 30) on the inner surface of the applicator housing 2902 that defines a linear movement path of the needle carrier assembly 2908 (similar to the tracks 622a-622c of FIG. 6). FIG. 30 further shows a channel 3002 configured such that when the spring 2912 rotates the rotational drive element 2914 relative to the needle carrier assembly 2908, the ridge 2916 of the rotational drive element 2914 slides therein. FIG. 30 further shows an insertion element 3074 coupled to the needle carrier assembly 2908.

[0193] In some embodiments, the holder 2924 further includes a retaining element 3042 configured to engage with a retaining element (not shown in Figure 30) of the applicator housing 2902, similar to the stop element 644 of the applicator housing 462 in Figure 6, and to fix the holder 2924 to the applicator housing 2902 when the needle carrier assembly 2908 reaches the distal insertion position. Not shown in Figure 30, the holder 2928 may further include a projection, and the applicator housing 2902 may further include a projection configured to prevent the holder 2924 from moving distally beyond the distal insertion position, similar to the projections 652 and 654 described above in relation to Figure 6F.

[0194] Figure 31 shows a cross-sectional view of yet another applicator 3100 for a skin sensor assembly of an analyte sensor system according to several embodiments. In some embodiments, the applicator 3100 may include an applicator housing 3102 configured to house one or more mechanisms for applying the skin sensor assembly 160 to the skin 130 of a recipient. The applicator 3100 may further include a base 3130 coupled to the applicator housing 3102 and configured to form the bottom of the applicator 3100.

[0195] The applicator 3100 further includes an actuation element (not shown in Figure 31) configured to actuate the drive assembly 3110 of the applicator 3100. In some embodiments, the actuation element may be a button, switch, toggle, slide, trigger, knob, rotating member, deformable and / or bendable component, or any other suitable mechanism for actinguating the drive assembly of the applicator 3100. In addition, the actuation element of the applicator 3100 may be positioned and oriented in any position and orientation with respect to the applicator housing 3102, for example, the top, any part of the side, or the bottom of the applicator housing 3102, and / or at any angle with respect to the part of the applicator housing 2102 in which the actuation element is disposed. The applicator 3100 may further include a needle carrier assembly 3108, which includes an insertion element 3174 releasably coupled to the skin sensor assembly 160 and configured to insert the sensor 138 of the skin sensor assembly 160 (e.g., Figure 1) into the skin 130 of the recipient. In some embodiments, the insertion element includes a needle, such as a single-ended needle, a needle with a deflected tip, a curved needle, a polymer-coated needle, a subcutaneous injection needle with a deflected tip, or any other suitable type of needle or structure, as will be described in more detail in relation to at least Figures 47-50 and 80A-80B. In yet another embodiment, the insertion element may comprise a sensor 138 itself that is rigid enough to be partially inserted into the recipient's skin 130 with minimal or no structural support.

[0196] The drive assembly 3110 may be configured to drive the insertion element 3174 of the needle carrier assembly 3108 distally to the distal insertion position and proximal from the distal insertion position to the proximal retraction position. The drive assembly 3110 may include a guide member 3138, a spring 3112, a hub 3132, and a reverse toggle element 3136. The guide member 3138 may be coupled at a first end and / or a second end to at least one of the applicator housing 3102 and the base 3130. The spring 3112 may be disposed around the guide member 3138 such that the guide member 3138 extends substantially along the centerline of the spring 3112. The spring 3112 may be any preferred type of spring, e.g., a compression spring, and may have a first end coupled to the base 3130 and a second end coupled to a hub 3132 disposed on and moving along the guide member 3138. The spring 3120 may be configured to drive the drive hub 3132 proximal along the guide member 3138 as indicated by the arrow when the drive assembly 3110 is in operation. The reverse toggle element 3136 may function as a lever rotatably coupled to the base 3130 or the applicator housing 3102, with a pivot point substantially at or near its midpoint. The first end of the reverse toggle element 3136 may contact the projection 3134 of the hub 3132 for at least the first proximal portion of the hub 3132, and the second end of the reverse toggle element 3136 may contact the needle carrier assembly 3108. The insertion assembly 3108 may be slidably coupled to the guide member 3138 on the side of the hub 3132 opposite to the spring 3112.

[0197] During operation, when the drive assembly 3110 is actuated, the spring 3112 drives the hub 3132 proximal along the guide member 3138. In the first portion of movement along the guide member 3138, the projection 3134 of the hub 3132 contacts the first end of the reverse toggle element 3136, driving the needle carrier assembly 3138, and therefore the insertion element 3174 and the skin sensor assembly 160 distally to the second end of the reverse toggle element 3136. After the first portion of movement along the guide member 3138, the projection 3134 of the hub 3132 clears the first end of the reverse toggle element 3136 and contacts the portion of the needle carrier assembly 3138 that is slidably coupled to the guide member 3138. At this point, the needle carrier assembly 3108, the insertion element 3174, and the skin sensor assembly 160 are in the distal insertion position. For the second moving portion along the proximal guide member 3138, the hub 3132 is still driven by the spring 3112 to drive the needle carrier assembly 3108, and therefore the insertion element 3174, from the distal insertion position to the proximal retraction position in the proximal direction. In this way, the drive assembly 3110 converts the unidirectional, for example, proximal linear motion of the spring 3112 into reciprocating linear motion in the distal and then proximal directions.

[0198] Figure 32A shows an exploded perspective view of yet another applicator 3200 for a skin sensor assembly of an analyte sensor system, according to several embodiments. The applicator 3200 may include an applicator housing 3202 configured to house at least one mechanism used to apply the skin sensor assembly 160 to the skin 130 of a recipient. The applicator 3200 may further include a base 3230 coupled to a bottom opening of the applicator housing 3202. The base 3230 defines the bottom surface of the applicator 3200 and a plane for applying the skin sensor assembly 160 to the skin 130 of a recipient.

[0199] The applicator 3200 includes an actuation element 3204 configured to actuate the drive assembly of the applicator 3200. In some embodiments, the actuation element 3204 may be a button, switch, toggle, slide, trigger, knob, rotating member, deformable and / or bendable component, or any other suitable mechanism for actinguating the drive assembly of the applicator 460.

[0200] The applicator 3200 may further comprise a needle carrier assembly 3208, which includes an insertion element 3274 configured to insert a sensor 138 of a skin sensor assembly 160 into the skin 130 of a recipient (e.g., Figure 1). In some embodiments, the insertion element includes a needle, e.g., a single-opening needle, a needle with a deflected tip, a curved needle, a polymer-coated needle, a subcutaneous injection needle, or any other suitable type of needle or structure, as will be described in more detail in relation to at least Figures 47-50 and 80A-80B. In yet another embodiment, the insertion element may comprise a sensor 138 that is rigid enough to be partially inserted into the skin 130 of a recipient with minimal or no structural support.

[0201] The applicator 3200 may further include a holder 3224 configured to be releasably coupled to the needle carrier assembly 3208 and to guide the on-skin sensor assembly 160 while coupled to the needle carrier assembly 3208. Once the on-skin sensor assembly 160 is placed on the recipient's skin 130, as will be described in more detail below, the on-skin sensor assembly 160 can be detached from the holder 3224 and the needle carrier assembly 3208.

[0202] The applicator 3200 may further include a drive assembly configured to drive the insertion element 3274 of the needle carrier assembly 3208 distally to the distal insertion position and proximal from the distal insertion position to the proximal retraction position. The drive assembly 3210 may include a first spring 3212 and a second spring 3228. The first spring 3212 may be a compression spring or any preferred type of spring and may have a first end coupled to the applicator housing 3202 and a second end coupled to the holder 3224. The first spring 3212 is configured to drive the holder 3224, as well as the coupled needle carrier assembly 3208, insertion element 3274, and skin sensor assembly 160 distally to the distal insertion position when the drive assembly 3210 is actuated. At substantially the distal insertion position, the needle carrier assembly 3208 can be detached from the holder 3224 and the skin sensor assembly 160.

[0203] The second spring 3228 may be a compression spring or any preferred type of spring, and may have a first end coupled to the holder 3224 and a second end coupled to the needle carrier assembly 3208. The second spring 3228 is configured to drive the needle carrier assembly 3208 and the insertion element 3274 in the proximal direction from the distal insertion position to the proximal retraction position. In some embodiments, the first spring and / or the second spring can be pre-loaded, partially loaded, or unloaded.

[0204] Figure 32B shows an exploded perspective view 3250 of the insert element 3274, the second spring 3228, the holder 3224, and the needle carrier assembly 3208 coupled to the skin sensor assembly 160.

[0205] Figures 33A to 33E show perspective cross-sections of some feature parts of the applicator 3200 of Figures 32A to 32B according to several embodiments. Figure 33A shows a perspective cross-section of the entire applicator 3200, including the applicator housing 3202, the actuation element 3204, the first spring 3212, the needle carrier assembly 3208 coupled to the insertion element 3274, the holder 3224 coupled to the skin sensor assembly 160, and the base 3230. Each of these components may have at least the functionality described above in relation to Figures 32A to 32B.

[0206] Figure 33B shows an enlarged perspective section of the retaining element 3312 of the holder 3224, which is releasably coupled to the applicator housing 3202. The retaining element 3312 is configured to prevent the holder 3224 from moving distally and thus prevent the spring 3212 from being unloaded. The actuation mechanism 3204, when actuated, is configured to deflect the retaining element 3312 sufficiently to detach it from the applicator housing 3202, thereby releasing the holder 3224, which is driven distally by the spring 3212.

[0207] Figure 33C shows an enlarged perspective section of a retaining element 3342 of a needle carrier assembly 3208, configured to releasably couple the needle carrier assembly 3208 to a holder 3224. As shown, the retaining element 3342 may have an inclined surface configured to contact a projection (not shown in Figure 33) of the applicator housing 3202 or base 3230 (not shown in Figure 33) which is configured to deflect the retaining element 3342 sufficiently to detach the needle carrier assembly 3208 from the holder 3224 when the needle carrier assembly 3208 is in or near the distal insertion position.

[0208] Figure 33D shows a perspective view of several retaining elements 3372a, 3372b of the needle carrier assembly 3208, which pass through the holder 3224 and are configured to releasably couple the on-skin sensor assembly 160 to the holder 3224 and the needle carrier assembly 3208. As previously mentioned, at the distal insertion position, the deflection retaining element 3342 detaches the needle carrier assembly 3208 from the holder 3224, allowing the second spring 3228 to drive the needle carrier assembly 3208 proximal. When the needle carrier assembly 3208 is driven proximal, the retaining elements 3372a, 3372b detach from the on-skin sensor assembly 160. Although two retaining elements are shown, any number of retaining elements are possible. In some embodiments, the retaining elements 3372a, 3372b may include snap-fits, friction-fits, interference features, elastomer grips, and / or adhesives configured to connect the skin sensor assembly 160 to the needle carrier assembly 3208 and / or holder 3224. Furthermore, alternative mechanisms capable of performing such retaining and releasing operations will be described further, at least in reference to Figures 35A to 37C below.

[0209] Figure 33E shows a perspective section of the retaining element 3346 of the holder 3224 and the retaining element 3348 of the applicator housing 3202, which is configured to secure the needle carrier assembly 3208 to the holder 3346 when the needle carrier assembly 3208 reaches the distal insertion position. This interaction secures the insertion element 3274 in the proximal retracted position, thereby ensuring that the end of the insertion element 3274 does not protrude from the bottom of the applicator 3200.

[0210] A brief description of the operation of applicator 3200 is given below with reference to Figures 34A to 34F, and several perspective views of the applicator in operation shown in Figure 32 are provided for some embodiments.

[0211] Figure 34A shows the state of the applicator 3200 during operation. The actuation element 3204 is shown in the process of being actuated, for example, by being pressed down by the user. The actuation element 3204 deflects the holding element 3312 so that the holder 3224 is not hindered from moving distally. The holder 3224, needle carrier assembly 3208, insertion element 3274, first spring 3212, and second spring 3228 are all shown in their pre-actuation positions.

[0212] Figure 34B shows the applicator 3200 in operation. The actuation element 3204 is shown in the actuation position. The spring 3212 drives the holder 3224 and also drives the needle carrier assembly 3208, the insertion element 3274, and the skin sensor assembly 160 distally toward the distal insertion position.

[0213] Figure 34C shows the applicator 3200 in operation as the needle carrier assembly 3208 approaches the distal insertion position. The actuation element 3204 is shown in the actuation position. The insertion assembly 3208, insertion element 3274, holder 3224, and skin sensor assembly 160 are driven distally to the distal insertion position. At or near this distal insertion position, at least a portion of the insertion element 3274 and at least a portion of the sensor 138 of the skin sensor assembly 160 can be inserted into the recipient's skin. At this position, the retaining element 3342 is deflected by a portion of the applicator housing 3302 or base 3230, thereby detaching the needle carrier assembly 3208 from the holder 3224.

[0214] Figure 34D shows the applicator 3200 in operation. The actuation element 3204 is shown in the actuation position. The second spring 3228 drives the needle carrier assembly 3208 and the insertion element 3274 from the distal insertion position to the proximal position. Although not shown in Figure 34D, when the needle carrier assembly reaches the proximal retracted position, the retaining elements 3346 and 3348 engage with each other to fix the needle carrier assembly 3208 and the insertion element 3274 in the proximal retracted position, thereby maintaining the insertion element 3274 in the locked retracted position.

[0215] Figures 35A to 35C show cross-sectional views of the skin sensor assembly holding mechanism of the applicator 3200 of Figure 32 according to several embodiments. The holding mechanism described in relation to Figures 35A to 35C is similar to the holding mechanism described in relation to Figures 6A to 6H. Figure 35A shows the holding mechanism while the applicator 3200 is in a pre-operation state. The holding element 3372a is shown as part of the holder 3224 and is configured to releasably connect the skin sensor assembly 160 to the holder 3224 when the needle carrier assembly 3208 moves distally to the distal insertion position, and to detach the skin sensor assembly 160 from the holder 3224 when the needle carrier assembly 3208 moves proximal from the distal insertion position to the proximal retraction position. Specifically, the holding element 3372a may include a first end 3376a and a second end 3378a. The second end may be releasably coupled to the skin sensor assembly 160 in the pre-operation state. As previously stated, the retaining elements 3372a, 3372b may include snap-fits, friction-fits, interference features, elastomer grips, and / or adhesives configured to couple the skin sensor assembly 160 with the needle carrier assembly 3208 and / or holder 3224. Figure 35A further shows the applicator housing 3202 including an optional reinforcing element 3510 configured to prevent lateral movement of the retaining element 3372a in the proximal starting position, thereby supporting the releasable coupling of the second end 3378a of the retaining element 3372a to the skin sensor assembly 160.

[0216] Figure 35B shows the applicator 3200 in the distal insertion position after activation. As the needle carrier assembly 3208 moves distally to the distal insertion position, the retaining element 3342 of the needle carrier assembly 3208 is released from the holder 3224. The second end of the retaining element 3372a may still be releasably coupled to the cutaneous sensor assembly 160. Figure 35B further shows an optional reinforcement element 3510 which is no longer in physical contact with the retaining element 3372a in the distal insertion position, thereby allowing the second end 3378a of the retaining element 3372a to be detached from the cutaneous sensor assembly 160.

[0217] Figure 35C shows the applicator 3200 with the needle carrier assembly 3208 moving proximal from the distal insertion position. The retaining element 3342 of the needle carrier assembly 3208 detaches from the holder 3224 as the needle carrier assembly 3208 moves proximal, as it detached from the holder 3224 at the distal insertion position. As the needle carrier assembly 3208 moves proximal, the first end 3376a of the retaining element 3372a is deflected by the needle carrier assembly 3208, thereby detaching the second end 3378a of the retaining element 3372a from the surface sensor assembly 160. Figure 35C further shows an optional reinforcement element 3510 that is no longer in physical contact with the retaining element 3372a at the distal insertion position.

[0218] Figures 36A to 36C show several cross-sectional views of the skin sensor assembly holding mechanism of the applicator 3200 of Figure 32, according to several embodiments. Figure 36A shows the holding mechanism while the applicator 3200 is in a pre-operation state. The holding element 3372a is shown as part of the needle carrier assembly 3208 and is configured to releasably connect the skin sensor assembly 160 to the holder 3224 when the needle carrier assembly 3208 moves distally to the distal insertion position, and to disconnect the skin sensor assembly 160 from the holder 3224 when the needle carrier assembly 3208 moves proximal from the distal insertion position toward the proximal retraction position. Specifically, the holding element 3372a can releasably connect the skin sensor assembly 160 when the needle carrier assembly 3208 moves distally to the distal insertion position. Figure 36A further illustrates the applicator housing 3202, which includes an optional reinforcing element 3610 configured to prevent lateral movement of the retaining element 3372a and / or retaining element 3342 at the proximal starting position, thereby supporting a releasable coupling between the retaining element 3372a and the skin sensor assembly 160.

[0219] Figure 36B shows the applicator 3200 in the distal insertion position. The retaining element 3342 of the needle carrier assembly 3208 is detached from the holder 3224 in the distal insertion position, and the retaining element 3224 is deflected by the applicator housing 3202 or the applicator base of the applicator housing 3202 to the extent that the retaining element 3224 clears the stop element of the needle carrier assembly. Thus, when the needle carrier assembly 3208 is returned in the proximal direction by the force provided by the spring 3228, the needle carrier assembly 3208 separates from the holder 3224. Rather than the orientation being physically deflected when the needle carrier assembly 3208 moves in the proximal direction, the retaining element 3372a is formed to easily deflect or deform simply to separate the holder 3224 from the needle carrier assembly 3208. Figure 36B further illustrates an optional reinforcing element 3610 that is no longer in physical contact with the retaining element 3372a and / or retaining element 3342 at the distal insertion position, thereby enabling the detachment of the retaining element 3372a from the skin sensor assembly 160 and / or the detachment of the holder 3224 from the needle carrier assembly 3208.

[0220] Figure 36C shows the needle carrier assembly 3208 moving proximal from the distal insertion position in Figure 36B. As shown, the retaining element 3372a is released from the skin sensor assembly 160 by separating the needle carrier assembly 3208 from the holder 3224, and the needle carrier assembly 3208 is driven proximal by a force provided by the spring 3228. Figure 36C further shows an optional reinforcing element 3610 when it is no longer in physical contact with the retaining element 3372a and / or retaining element 3342 in the proximal retraction position.

[0221] Figures 37A to 37C show several cross-sectional views of yet another skin sensor assembly holding mechanism of the applicator 3200 of Figure 32, according to several embodiments. Figure 37A shows the applicator 3200 in the pre-operation position. The holding element 3372a, shown in Figure 37A as an integral part of the holder 3208, is configured to releasably connect the skin sensor assembly 160 to the holder 3224 when the needle carrier assembly 3208 moves distally to the distal insertion position, and to disconnect the skin sensor assembly 160 from the holder 3224 when the needle carrier assembly 3208 moves proximal from the distal insertion position to the proximal retraction position. Specifically, the holding element 3372a can releasably connect the skin sensor assembly 160 when the needle carrier assembly 3208 moves distally to the distal insertion position. Figure 37A further illustrates an applicator housing 3202 comprising an optional first reinforcing element 3710 configured to prevent lateral movement of the retaining element 3342 in the proximal retracted position. Figure 37A further illustrates a needle carrier 3208 comprising an optional second reinforcing element 3712 configured to prevent lateral movement of the retaining element 3372a, thereby supporting a releasable coupling between the retaining element 3372a and the skin sensor assembly 160.

[0222] Figure 37B shows the needle carrier assembly 3208 in the distal insertion position. The retaining element 3342 of the needle carrier assembly 3208 is detached from the holder 3224 in the distal insertion position. Thus, the needle carrier assembly 3208 detaches from the holder 3224 as the needle carrier assembly 3208 returns proximal under the influence of the force provided by the spring 3228 when the spring 3228 unloads and pushes the holder 3224 and the needle carrier assembly 3208. Figure 37B further shows an optional first reinforcement element 3710 which no longer has physical contact with the retaining element 3342 in the distal insertion position, thereby enabling the detachment of the holder 3224 from the needle carrier assembly 3208. An optional second reinforcement element 3712 is still shown as being in physical contact with the retaining element 3372a in the distal insertion position.

[0223] Figure 37C shows the needle carrier assembly 3208 as it begins to move proximal after the retaining element 3372a of the needle carrier assembly 3208 has been detached from the holder 3224. As shown in Figures 35A–35C, rather than the orientation being physically deflected as the needle carrier assembly 3208 moves proximal, the retaining element 3372a detaches from the on-skin sensor assembly 160 simply by the user removing the applicator 3200 from the skin. In some embodiments, the adhesive patch that holds the on-skin sensor assembly 160 to the recipient's skin provides sufficient bonding strength to detach the on-skin sensor assembly 160 from the recipient's skin when the applicator 3200 is removed from the skin. Figure 37C further shows an optional first reinforcing element 3710 that ceases to be in physical contact with the retaining element 3372a in the proximal retracted position, thereby supporting the detachment of the retaining element 3372a from the on-skin sensor assembly 160.

[0224] Figure 38 shows a perspective view of an applicator 3800, similar to those shown in Figure 32, which includes an actuation element 3804 on the side of the applicator housing 3802, according to several embodiments. The applicator 3800 may have substantially the same features as any of the applicators 3200 in Figure 32, except that the actuation element 3804 is located on the side of the applicator housing 3802 rather than on the top of the applicator housing. Such a configuration may provide an applicator that is wider or in diameter compared to a top-actuated applicator, but lower in height compared to a top-actuated applicator.

[0225] Figure 39 shows a section view of a portion of the applicator 3800 of Figure 38 according to several embodiments. The actuation element 3804 may be configured to deflect the retaining element 3902 of the holder 3824, which is configured to prevent the holder 3824 from moving distally during operation. All other features of the applicator 3800 that are not discussed may be substantially as described previously for any of the applicators 3200 in Figure 32.

[0226] Figures 40A to 40G show several perspective views of the assembly process of the applicator of Figure 32 according to several embodiments. Figure 40A shows the step of inserting the second spring 3228 into the holder 3224. Figure 40B then shows the step of inserting the insertion element 3274 into the needle carrier assembly 3208, and then inserting the insertion element 3274 into the holder 3224 into the needle carrier assembly 3208. In some embodiments, when the insertion element 3274 is inserted into the holder 3224 into the needle carrier assembly 3208, the second spring 3228 is pre-compressed. Figure 40C shows the step of connecting the skin sensor assembly 160 to at least one of the holder 3224 and the needle carrier assembly 3208 by coupling a retaining element (not shown in Figure 40C) of the holder 3224 or the needle carrier assembly 3208 to a mounting point (not shown in Figure 40C) of the skin sensor assembly 160.

[0227] Figure 40D shows the step of coupling the actuation element 3204 to the applicator housing 3202. In Figure 40D, the actuation element 3204 is coupled on the top of the applicator housing 3202. In some embodiments, the actuation element 3204 may be pressed into an opening in the applicator housing 3202 configured to receive the actuation element 3204. However, in other embodiments, the applicator housing 3202 may house the actuation element 3204 in other positions, for example, on the upper side, inside, or below the applicator housing. Figure 40E shows the step of inserting the first spring 3212 into the applicator housing 3202. Figure 40F shows the step of inserting the assembly shown in Figure 40C (comprising a holder 3224, a second spring 3228, a needle carrier assembly 3208, an insertion element 3274, and a skin sensor assembly 160) into the applicator housing 3202. In some embodiments, the act of inserting the assembly shown in Figure 40C pre-compresses the first spring 3212. Figure 40G shows the step of coupling the base 3230 to the applicator housing 3202.

[0228] Skin-surface sensor assembly holding mechanism In some embodiments of the applicators described herein, the skin sensor assembly 160 is held in place while moving at least distally to the distal insertion position. In some such embodiments, the skin sensor assembly 160 is released or detached from a portion of the applicator during application to the recipient's skin so that the skin carrier assembly and insertion element can return proximal. Figures 41A to 45 show some alternative retention mechanisms that may be used in any of the applicators described herein.

[0229] Figures 41A to 41B show exemplary skin sensor assembly holding mechanisms for applicators of analyte sensor systems according to several embodiments. The holding mechanisms shown in Figures 41A to 41B can be considered a first skin sensor assembly holding configuration and are similar to the holding mechanisms described above in relation to Figure 5.

[0230] Figure 41A shows the holding mechanism in the state where the skin-borne sensor assembly 160 is held, and Figure 41B shows the holding mechanism in the state where the skin-borne sensor assembly 160 is detached.

[0231] Figure 41A shows retaining elements 4172a, 4172b of the holder 4124, which are configured to releasably connect the skin sensor assembly 160 to the holder 4124 when the needle carrier assembly 4108 (and thus the insertion element 4172, the holder 4124, and the skin sensor assembly 160) moves distally to the distal insertion position. Specifically, the retaining elements 4172a, 4172b may each include first ends 4176a, 4176b, second ends 4178a, 4178b, and pivot points 4180a, 4180b. The first ends 4176a, 4176b are fixed to the respective guides 4174a, 4174b of the needle carrier assembly 4108, and the respective retaining elements 4172a, 4172b are fixed to the interference points 4182a, 4182b of the needle carrier assembly 4108, thereby releasably connecting and fixing the second end 4178a to the mounting points 4162a, 4162b of the skin sensor assembly 160 as the needle carrier assembly 4108 moves distally to the distal insertion position. In some embodiments, the profiles of slots 4174a, 4174b may be such that the sides of slots 4174a, 4174b exert sufficient force on the first ends 4176a, 4176b of the retaining elements 4172a, 4172b to hold the second ends 4178a, 4178b of the retaining elements 4172a, 4172b that engage with the mounting points 4162a, 4162b of the skin sensor assembly 160. Although two retaining elements are shown, any number of retaining elements are conceivable.

[0232] Figure 41B shows the retention mechanism as the needle carrier assembly 4108 and insertion element 4174 move proximal from the distal insertion position to the proximal retraction position. When the needle carrier assembly 4108 returns proximal, it separates from the holder 4124, thereby dislodging the first ends 4176a, 4176b of the retention elements 4172a, 4172b from their respective slots 4174a, 4174b, and deflecting the first ends 4176a, 4176b inward, while the second ends 4178a, 4178b of the retention elements 4172a, 4172b are deflected outward from the mounting points 4162a, 4162b of the skin sensor assembly 160 as the retention elements 4172a, 4172b rotate around the pivot points 4180a, 4180b.

[0233] Figures 42A to 42B show exemplary skin sensor assembly holding mechanisms for applicators of analyte sensor systems according to several embodiments. The holding mechanisms shown in Figures 42A to 42B can be considered a second skin sensor assembly holding configuration and are similar to the holding mechanisms described above in relation to Figure 36. Figure 42A shows the holding mechanism with the skin sensor assembly 160 held, and Figure 42B shows the holding mechanism with the skin sensor assembly 160 detached.

[0234] Figure 42A shows the retaining elements 4272a and 4272b not as parts of the holder 4224, but as parts of the needle carrier assembly 4208 that pass through or around the needle carrier assembly 4208. The retaining elements 4272a and 4272b are configured to releasably connect the needle carrier assembly 4208 (and therefore the insertion element, holder 4224, and the cutaneous sensor assembly 4224) to the holder 4228 as the needle carrier assembly 4208 moves distally to the distal insertion position.

[0235] Figure 42B shows the retention mechanism as the needle carrier assembly 4208 and insertion element 4274 move proximal from the distal insertion position to the proximal retraction position. As the needle carrier assembly 4208 moves proximal, the needle carrier assembly 2508 separates from the holder 4224, and the retention elements 4272a and 4272b are detached from their respective mounting points 4262a and 4262b on the skin sensor assembly 160. Rather than being physically oriented as the needle carrier assembly 4208 moves proximal, the retention elements 4272a and 4272b are pulled away from their mounting points 4262a and 4262b by the retraction energy, as described for the retention elements 4172a and 4172b in Figures 41A and 41B.

[0236] Figures 43A and 43B show exemplary skin sensor assembly holding mechanisms for applicators of analyte sensor systems according to several embodiments. The holding mechanisms shown in Figures 43A and 43B can be considered passive snap designs. Figure 43A shows the holding mechanism with the skin sensor assembly 160 held, and Figure 43B shows the holding mechanism with the skin sensor assembly 160 detached.

[0237] Figure 43A shows retaining elements 4372a and 4372b as part of the holder 4324. The retaining elements 4372a and 4372b are configured to releasably couple the skin sensor assembly 160 to the holder 4324 as the needle carrier assembly 4308 (and thus the insertion element, holder 4324, and skin sensor assembly 4324) moves distally to the distal insertion position. Figure 43A further shows projections 4380a and 4380b of the needle carrier assembly 4308 configured to physically contact the retaining elements 4372a and 4372b of the holder 4324, thereby preventing the retaining elements 4372a and 4372b from detaching from the skin sensor assembly 4324 while the needle carrier assembly 4308 is in contact with the holder 4324.

[0238] Figure 43B shows the retention mechanism as the needle carrier assembly 4308 moves proximal from the distal insertion position to the proximal retraction position. As the needle carrier assembly 4308 moves proximal, it separates from the holder 4324. Although not shown in Figures 43A to 43B, the holder 4324 may be secured to the applicator housing or base by one or more retention elements similar to the retention elements 642, 644 in Figure 6E. Thus, the retention elements 4372a, 4372b can be detached from their respective mounting points 4362a, 4362b of the on-skin sensor assembly 160 when the applicator is removed from the recipient's skin. In some embodiments, the adhesive patch that holds the on-skin sensor assembly 160 to the recipient's skin provides sufficient bonding strength to detach the on-skin sensor assembly 160 from the recipient's skin when the applicator is removed from the skin.

[0239] Figure 44 shows another part of an exemplary on-skin sensor assembly holding mechanism for an analyte sensor system applicator, according to several embodiments. Figure 44 shows a needle carrier assembly 4408, a holder 4424, and an on-skin sensor assembly 160. Unlike some previous embodiments of the holding mechanism for the on-skin sensor assembly 160, the needle carrier assembly 4408 comprises at least one retaining element 4472a, and the holder 4424 comprises at least one alignment element 4473a, wherein the retaining element 4472a is configured to be releasably coupled to the on-skin sensor assembly 160, and the alignment element 4473a is configured to align the on-skin sensor assembly 160 within the applicator. This distribution of retaining elements between both the needle carrier assembly and the holder may be implemented for any on-skin sensor assembly holding mechanism described herein.

[0240] Figures 45 and 46 show portions of exemplary skin sensor assembly holding mechanisms of an applicator for an analyte sensor system according to several embodiments. Figures 45 and 46 show needle carrier assemblies 4508, 4608, rotary drive elements 4514, 4614 similar to those described above in relation to Figure 5, and a skin sensor assembly 160. Thus, the holding mechanisms of Figures 45 and 46 may function similarly to those described in Figure 5. The rotary drive elements 4514, 4614 may be wheel cams and may include cam lobes 4518 (e.g., ramps or projections not shown in Figure 46, see Figure 45) arranged along at least a portion of the circumference of the rotary drive elements 4514, 4614. In Figure 45, as the rotary drive element 4514 rotates, the projection 4518 can move along the needle carrier assembly 4508, contact the skin sensor assembly 160, and apply an increasing force to it, so that the skin sensor assembly 160 is detached from the needle carrier assembly 4508. In Figure 46, as the rotary drive element 4614 rotates, the projection can at least partially pass through the guide or slot 4620 of the needle carrier assembly 4608, contact the skin sensor assembly 160, and apply an increasing force to it, so that the skin sensor assembly 160 is detached from the needle carrier assembly 4608. In this way, both the rotary drive elements 4514 and 4614 can drive the needle carrier assemblies 4508 and 4608 distally and proximal, as described above in relation to Figure 5, and release the skin sensor assembly 160 upon deposition on the recipient's skin.

[0241] In some embodiments, the skin sensor assembly holding mechanism may incorporate a feature that connects the skin sensor assembly to the needle carrier assembly and / or holder. A method for connecting the skin sensor assembly is described in U.S. Patent Application No. 15 / 387088, which is incorporated herein by reference in its entirety. In non-limiting examples, the skin sensor assembly holding mechanism may include a fragile release (e.g., Figures 137–140), a fragile elastomer (e.g., Figures 134–136), a peelable adhesive (e.g., Figures 123–125), or a removable friction fit coupling (e.g., Figures 126–133).

[0242] For example, in the present embodiment, a fragile release can be implemented by a structure mounted between the skin sensor assembly (e.g., 160), the holder (e.g., 524), the needle carrier (e.g., 508), and / or the applicator housing (e.g., 502). The fragile component may include a feature portion having a weakened portion or a portion designated to break during the release of the skin sensor assembly from the applicator. Examples of fragile components configured to break include patch material (e.g., spunlace) or molded components (e.g., ABS, PC, polymer, elastomer polymer, etc.).

[0243] For example, in the present embodiment, the peelable adhesive can be implemented by a peelable adhesive that is releasably attached between the skin sensor assembly (e.g., 160), the holder (e.g., 524), the needle carrier (e.g., 508), and / or the applicator housing (e.g., 502). The peelable adhesive may consist of double-sided adhesive tape, adhesive, or hot-melt polymer. The peelable adhesive is configured to detach when the skin sensor assembly is released from the applicator via the applicator mechanism (e.g., retraction mechanism) or user force.

[0244] For example, in the present embodiment, a releasable friction fit coupling can be implemented by surface contact between a skin sensor assembly (e.g., 160), a holder (e.g., 524), a needle carrier (e.g., 508), and / or an applicator housing (e.g., 502). The releasable friction fit coupling may consist of a rigid or elastomer material (e.g., silicone, TPE, TPU, rubber, etc.) or a combination thereof. The coupled components (e.g., skin sensor assembly 160 and holder 524) have an interaction of friction materials (e.g., an interlocking fit, a deformable fit, etc.). The releasable friction fit coupling is configured to separate during the release of the skin sensor assembly from the applicator via an applicator mechanism (e.g., a retraction mechanism) or user force.

[0245] The following discussion relating to Figures 71–89 may, in particular, be directed to applicators illustrating skin tenting (e.g., skin that curves substantially convexly when the recipient presses the applicator against their skin). Figures 71–89 may further be directed to preventing stall of the insertion mechanism, assembly, or spring due to such skin tenting by initiating retraction after insertion, in other embodiments, based on the skin sensor assembly and / or other features of the applicator pressing against the recipient's skin with sufficient force to initiate retraction, as opposed to retraction triggered by the skin sensor assembly and other features of the applicator leading to a predetermined physical displacement distally. Such force-based retraction triggers may allow the transition from insertion to retraction at various distally displaced positions, at least partially based on the position of the recipient's skin surface during application.

[0246] Figure 71 shows an applicator 7100 for a skin sensor assembly of an analyte sensor system according to several embodiments. As described below, the applicator 7100 may include an actuation element 7104 disposed on a side of the applicator 7100, for example, on the side of the outer housing 7101 of the applicator 7100. In some embodiments, the actuation element 7104 may be a button, switch, toggle, slide, trigger, knob, rotating member, a part of the applicator 7100 that deforms and / or bends, or any other suitable mechanism for acting on the insertion and / or retraction assembly of the applicator 7100. In some embodiments, the actuation element 7104 may be disposed in any position, for example, on the top, upper, lower, or any other position of the applicator 7100. The applicator 7100 may be large enough for a recipient to grasp it in their hand and actuate the actuation element 7104 by pressing it with, for example, their thumb or index and / or middle finger.

[0247] The applicator 7100 may be configured with one or more safety features that prevent the applicator 7100 from operating until the safety feature is deactivated. In one embodiment, one or more safety features prevent the applicator 7100 from operating unless it is pressed against the recipient's skin with sufficient force. Furthermore, as will be described in more detail in relation to one or more of the following Figures 72 to 80B, the applicator 7100 may be further configured so that one or more components retract internally, at least in part, based 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 7100 may implement a force-based retraction trigger, rather than being limited to a displacement-based retraction trigger.

[0248] Figure 72 shows exploded perspective views of the applicator 7100 of Figure 71 according to several embodiments. The applicator 7100 may include an outer applicator housing 7101 with an actuation element 7104. The outer applicator housing 7101 may be configured to be translated distally by a force applied to the applicator 7100, particularly the inner housing 7102, by the receiver, thereby aligning the actuation element 7104 to a position where the applicator 7100 can be launched. A further description of the alignment process is given below.

[0249] The applicator 7100 further comprises an inner housing 7102 configured to house at least one mechanism used to apply the skin sensor assembly 360 to the recipient's skin 130. The distal surface 7130 of the bottom opening of the inner housing 7102 may define the bottom surface of the applicator 7100. In some embodiments, when the applicator 7100 is pressed against the recipient's skin 130, the skin 130 may deform substantially convex on the distal surface 7130 such that at least a portion of the surface of the skin 130 disposed at the bottom opening of the applicator housing 7102 extends proximal beyond the plane defined by the distal surface 7130 to the bottom opening of the inner housing 7102.

[0250] In some embodiments, the first barrier layer 7192 may be disposed over one or more openings in the inner housing 7102, for example, an opening 7106 which may be configured to extend through at least a portion of the actuation element 7104 during the operation of the applicator 7100. In such embodiments, a portion of the actuation element 7104 may be configured to penetrate or deform the first barrier layer 7192 during the operation of the applicator 7100. The first barrier layer 7192 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.

[0251] The applicator 7100 may further comprise a needle carrier assembly 7108 including a needle hub 7150 configured to couple an insertion element 7174 to the needle carrier assembly 7108. In some other embodiments, the insertion element 7174 may be directly coupled to the needle carrier assembly 7108. The insertion element 7174 is configured to insert the sensor 338 of the on-skin sensor assembly 360 (see Figures 3A–4) into the skin 130 of the recipient (e.g., Figure 1). In some embodiments, the insertion element comprises a needle, e.g., a single-opening needle, a needle with a deflected tip, a curved needle, a polymer-coated needle, a subcutaneous injection needle, or any other suitable type of needle or structure, as described in relation to at least Figures 47–50 and 80A–80B. In yet another embodiment, the insertion element 7174 may be formed integrally with the sensor 338 and may be rigid enough to be partially inserted into the skin 130 of the recipient with minimal or no structural support.

[0252] The applicator 7100 is releasably coupled to the needle carrier assembly 7108 and may further include a holder 7124 configured to guide the needle carrier assembly 7108 and the cutaneous sensor assembly 360 while coupled to the needle carrier assembly 7108, for example, during translation from at least a proximal position to a distal insertion position. Once the cutaneous sensor assembly 360 is positioned on the recipient's skin 130, as will be described in more detail below, the cutaneous sensor assembly 360 may be detached or released from the holder 7124 and the needle carrier assembly 7108.

[0253] The applicator 7100 may further comprise an insertion assembly configured to translate the insertion element 7174, the needle hub 7150, the needle carrier assembly 7108, and the skin sensor assembly 360 from a proximal position to a distal insertion position. Such an insertion assembly may include a first spring 7112. The first spring 7112 may be a compression spring or any preferred type of spring and may have a first end in contact with or coupled to the inner applicator housing 7102 and a second end in contact with or coupled to the holder 7124. The first spring 7112 is configured to translate the holder 7124, the needle carrier assembly 7108, the needle hub 7150, the insertion element 7174, and the skin sensor assembly 360 distally to a distal insertion position when the insertion assembly is actuated. At a substantially distal insertion position, the needle carrier assembly 7108 can be detached from the holder 7124 and the skin sensor assembly 360.

[0254] The applicator 7100 may further include a retraction assembly configured to translate the needle carrier assembly 7108, the needle hub 7150, and the insertion element 7174 in the proximal direction from the distal insertion position to the 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 a second spring 7128. The second spring 7128 may be a compression spring or any preferred type of spring and may have a first end in contact with or coupled to the holder 7124 and a second end in contact with or coupled to at least one spring retaining element (e.g., 7442a, 7442b in Figures 74A to 75B) at least until retraction. The second spring 7128 is configured to translate the needle carrier assembly 7108, needle hub 7150, and insertion element 7174 in the proximal direction from the distal insertion position to the proximal retraction position, depending on the on-skin sensor assembly 360 that is in contact with the recipient's skin 130, and / or for the first end of the second spring 7128 to reach a movement limit with a force exceeding a predetermined threshold sufficient to overcome at least one spring retaining element (e.g., 7442a, 7442b in Figures 74A to 75B). In some embodiments, a stopping feature (not shown) may be located at the bottom of the applicator 7100, for example, in the distal portion of the inner housing 7102. Such a stopping feature may be configured to contact one or more of the on-skin sensor assembly 360, needle carrier 7108, or holder 7124 at the distal insertion position.

[0255] In some embodiments, movement of the on-skin sensor assembly 360 between insertion and withdrawal may occur, for example, as described above in relation to any of Figures 35A to 37C.

[0256] In some embodiments, the second barrier layer 7194 may be located above the bottom opening of the inner housing 7102. The second barrier layer 7194 may include a gas-permeable material such as Tyvek, or a gas-impermeable material such as a metal foil or film. In some embodiments, the second barrier layer 7194 may be removed by the recipient before use of the applicator 7100. In embodiments including one or both of the first and second barrier layers 7192, 7194, such layers may provide a sterile environment between the applicator 7100 and the external environment and / or allow gas to enter and exit during sterilization, etc.

[0257] Although not shown in Figures 71-72, in some embodiments the applicator 7100 may be configured to be fixed to the distal surface 7130 of the inner housing 7102 and may include a cap that can be removed before use. In some embodiments, such a cap may also function as a sterile barrier, as described above in U.S. Patent Application No. 16 / 011527, which is incorporated herein in its entirety by reference.

[0258] A brief description of some aspects of the operation of the applicator 7100 follows with respect to Figures 73A to 73C, which show several cross-sectional views of the applicator 7100 in operation in Figures 71 and 72 according to several embodiments. Figures 73A to 73C may correspond, for example, to the applicator 7100 cut along the cutting line A-A' shown in Figure 71.

[0259] Figure 73A shows the state of the applicator 7100 before operation. The holder 7124 includes an insertion assembly retaining element 7332 configured to contact the inner housing 7102, thereby securing the holder 7124, the needle carrier assembly 7108, the needle hub 7150, the insertion element 7174, and the skin sensor assembly 360 in the pre-operation state.

[0260] The needle carrier assembly 7108 comprises a plurality of wearable retaining elements and / or alignment elements 7372a, 7372b that extend through the holder 7124 and are configured to releasably connect the on-skin sensor assembly 360 to the holder 7124 and / or the needle carrier assembly 7108. The wearable retaining elements 7372a, 7372b may include, for example, arms, deflection elements, tabs, stoppers, snaps, or any other feature parts capable of retaining function. In some embodiments, the wearable retaining elements 7372a, 7372b may extend around the holder 7124 rather than through it. Although two wearable retaining elements are shown, any number of wearable retaining elements are conceivable. In some embodiments, the wearable retention elements 7372a, 7372b may include snap-fits, friction-fits, interference features, elastomer grips, and / or adhesives configured to connect the skin sensor assembly 360 to the needle carrier assembly 7108 and / or holder 7124.

[0261] The inner housing 7102 may include a spring 7320 configured to contact the outer housing 7101 and maintain a predetermined distance between the outer housing 7101 and the inner housing 7102 in the pre-actualized orientation shown in Figure 73A. The spring 7320 may be a compression spring, a leaf spring, a bend-arm spring, foam, or rubber, etc. In some other embodiments, the outer housing 7101 may also include a spring 7320, which may be configured to contact the inner housing 7102 in the opposite manner to that shown in Figure 73A.

[0262] The operation of the applicator 7100 may involve the recipient pressing the applicator 7100 against the skin with sufficient force to translate the outer housing 7101 distally to the inner housing 7102, as indicated by arrow 7302, until the actuation element 7104 aligns with the opening 7106 of the inner housing 7102 and the insertion assembly retaining element 7332 of the holder 7124. The insertion assembly retaining element 7332 may comprise, for example, arms, deflection elements, tabs, return mechanisms, snaps, or any other features capable of retaining functions. Once such alignment is achieved, the recipient can initiate (e.g., push) the actuation element 7104, as indicated by arrow 7304, thereby deflecting the insertion assembly retaining element 7332 sufficiently to release the holder 7124 from the inner housing 7102. In some other embodiments, the applicator 7100 may be configured such that the actuation element 7104 is initially actuated, but actual insertion is not triggered until the outer housing 7101 has sufficiently translated distally relative to the inner housing 7102. In yet another embodiment, the actuation element 7104 may be biased toward the center of the applicator 7100 so that it does not need to be explicitly actuated by the recipient, but instead, the actuation element 7104 may be configured to automatically initiate insertion once the outer housing 7101 has sufficiently translated distally relative to the inner housing 7102.

[0263] Such a configuration has several advantages. Firstly, the translation of the outer housing 7101 relative to the inner housing 7102 before activation provides a means of fall protection so that the applicator 7100 does not fire prematurely if it is accidentally dropped. Secondly, the spring 7320 provides a biasing force that the receiver must actively overcome by pressing the applicator 7100 against the skin before firing, thereby reducing the possibility of activating the applicator 7100 before it is properly positioned. Furthermore, the receiver may decide not to fire the applicator 7100 and to cease pressing the applicator 7100 against the skin, allowing the spring 7320 to bias the outer housing 7101 and return the outer housing 7101 to its initial position.

[0264] The holder 7124, needle carrier assembly 7108, needle hub 7150, insertion element 7174, skin sensor assembly 360, first spring 7112, and second spring 7128 are all shown in the pre-operation position in Figure 73A.

[0265] Figure 73B shows the applicator 7100 before the needle carrier assembly 7108 is retracted, with the cutaneous sensor assembly 360 being inserted. The first spring 7112 drives the holder 7124, the needle carrier assembly 7108, the needle hub 7150, the insertion element 7174, and the cutaneous sensor assembly 360 distally toward the distal insertion position. Figure 73B shows the position where the cutaneous sensor assembly 360 is in contact with the recipient's skin 130, but the holder 7124 has not yet been fully driven by the first spring 7112 to contact the cutaneous sensor assembly 360 or the recipient's skin 130.

[0266] In some embodiments, the masses of the holder 7124, needle carrier assembly 7108, needle hub 7150, insertion element 7174, and skin sensor assembly 360 may be specifically designed to reduce or substantially eliminate the tendency for the needle carrier assembly 7108, needle hub 7150, insertion element 7174, and skin sensor assembly 360 to detach from the holder 7124 due to inertial forces while they are driven distally during insertion. In some embodiments, the force exerted by the first spring 7112 may be selected to be sufficient for the proper operation of the applicator 7100, but not so large as to further exacerbate the inertially triggered detachment described above. In some embodiments, a spring (not shown) may be configured to apply a force sufficient to prevent the needle carrier assembly 7108 from being inertially triggered to detach from the holder 7124 during insertion, for example, distally to a portion of the needle carrier assembly 7108.

[0267] Figure 73C shows the applicator 7100 in operation when the needle carrier assembly 7108, needle hub 7150, and insertion element 7174 are retracted proximal by the second spring 7128. In Figure 73C, the first spring 7112 has a skin sensor assembly 360 fully driven against the recipient's skin. In this position, the second spring 7128 is released from the spring retaining element (e.g., 7442a, 7442b in Figures 74A–75B) and drives the needle carrier assembly 7108, needle hub 7150, and insertion element 7174 proximal from the distal insertion position. When the needle carrier assembly 7108 reaches the proximal retracted position, the needle carrier retaining element 7334 of the holder 7124 engages with the needle carrier assembly 7108, thereby maintaining the needle carrier assembly 7108, the needle hub 7150, and the insertion element 7174 in a locked retracted position, and restricting access to the insertion element 7174. The needle carrier retaining element 7334 may include, for example, an arm, a deflection element, a tab, a stopper, a snap, or any other feature capable of retaining. In this retracted position, the needle carrier assembly 7108, the needle hub 7150, and the insertion element 7174 are prevented from moving distally.

[0268] A further description of some aspects of the operation of the applicator 7100 follows with respect to Figures 74A to 74C, which show several cross-sectional views of the applicator 7100 in operation in Figures 71 and 72 according to several embodiments. Figures 74A to 74C may correspond, for example, to the applicator 7100 cut along the cutting line B-B' shown in Figure 71. For simplicity of explanation, the needle hub 7150 and insertion element 7174 are not shown in Figures 74A to 74C.

[0269] Figure 74A shows the applicator 7100 in its pre-operation state. For simplicity of explanation, the skin sensor assembly 360 is not shown in Figure 74A. The holder 7124 includes spring retaining elements 7442a, 7442b configured to contact and hold the first end of the second spring 7128 in its pre-operation state, for example during insertion, while the second end of the spring 7128 is in contact with the needle carrier assembly 7108. The spring retaining elements 7442a, 7442b may include, for example, arms, deflection elements, tabs, stoppers, snaps, or any other feature parts capable of retaining functions. Although two spring retaining elements 7442a, 7442b are shown, at least one spring retaining element is conceivable. In some embodiments, the applicator 7100 may include one spring retaining element, as shown in Figures 81A to 81D. In some embodiments, the applicator 7100 may include three spring retaining elements. In some embodiments, the applicator 7100 may include four spring retaining elements. In some embodiments, the spring retaining elements 7442a, 7442b are deflectable arms, rigid arms, deformable features, snaps, catches, or hooks. In some embodiments, the spring retaining elements 7442a, 7442b may be actively deflected by one or more features within the applicator 7100.

[0270] The needle carrier assembly 7108 includes, for example, backstop features 7444a, 7444b configured to prevent lateral deflection of the spring retaining elements 7442a, 7442b at least in the proximal starting position during insertion, thereby supporting the retention of the second spring 7128 between the spring retaining elements 7442a, 7442b and the holder 7124 until retracted. Although two backstop features are shown, any number of backstop features is possible. The number of backstop features may be equal to the number of spring retaining elements.

[0271] Figure 75A shows an enlarged view of the spring retaining element 7442b and the backstop feature 7444b. In Figure 75A, the first spring 7112 drives the holder 7124, the needle carrier assembly 7108, and the skin sensor assembly 360 distally toward the distal insertion position. The backstop feature 7444b is shown engaged with the spring retaining element 7442b to prevent the spring retaining element 7442b from deflecting laterally, thereby preventing the second spring 7128 from releasing. As shown in Figure 75A, the proximal end of the spring retaining element 7442b may be offset from the distal end of the backstop feature 7444b by a distance α. In some embodiments, the distance α is the length required for the spring retaining element 7442b to traverse along the backstop feature 7444b so that the spring retaining element 7442b clears past the backstop feature 7444b. The backstop feature 7444b may feature an inclination to guide the spring retaining element 7442b. The distal end of the needle carrier assembly 7108 and the distal end of the holder 7124 may be offset from each other by at least the same distance α to allow the spring retaining element 7442b to traverse distally beyond the backstop feature 7444b.

[0272] It can be understood that the frictional force between the corresponding contact surface of the backstop feature 7444b and the spring retaining element 7442b can at least partially determine the amount of force that releases the spring retaining element 7442b from the backstop feature 7444b. This force can allow the spring retaining element 7442b to deflect laterally and thus allow the second spring 7128 to expand. In some embodiments, the amount of force is at least 0.1 pounds. In some embodiments, the amount of force is at least 0.5 pounds. 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.

[0273] This figure shows a backstop feature portion 7444b that prevents lateral deflection of the radially outward-facing spring retaining element 7442b, but it is considered that the opposite structural relationship can be achieved. For example, as shown in Figure 75A, the inclined surface of the spring retaining element 7442b can be reversed so that it faces in the opposite direction. Furthermore, the inclined surface of the spring retaining element 7442b may be biased radially inward relative to the backstop feature portion 7444b by the second spring 7128. In such an embodiment, the backstop feature portion 7444b may be located radially inward of the spring retaining element 7442b.

[0274] Therefore, in some embodiments, the material used to form the holder 7124 and the needle carrier assembly 7108 may be selected based on the desired amount of force to release the spring retaining element 7442b for lateral deflection. Examples of such materials include polycarbonate, ABS, PC / ABS, polypropylene, HIPS (high-impact polystyrene), polybutylene terephthalate (PBT), polyoxymethylene (POM), acetal, polyacetal, polyformaldehyde, PTFE, high-density polyethylene (HDPE), nylon, polyethylene terephthalate (PET), thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), TPSiv, cycloolefin polymer (COP), cycloolefin copolymer (COC), and / or liquid crystal polymer (LCP).

[0275] The angle θ of the portion of the spring retaining element 7442b in contact with the second spring 7128 can also affect the amount of frictional force that laterally deflects the spring retaining element 7442b and thereby releases the second spring 7128. Therefore, the angle θ may be selected based on the desired amount of force that laterally deflects the spring retaining element 7442b sufficiently to release the second spring 7128. In some embodiments, the angle θ is at least 1 degree with respect to the vertical axis of the spring retaining element 7442b. 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 to 45 degrees. In addition, the force profile of the second spring 7128 can affect the target amount of frictional force that laterally deflects the spring retaining element 7442b. Therefore, in some embodiments, when selecting the angle θ of the material for forming one or both of the holder 7124 and the needle carrier assembly 7108 and the portion of the spring retaining element 7442b that contacts the second spring 7128, the force profile of the second spring 7128 may be taken into consideration.

[0276] The angle β of the spring retaining element 7442b with respect to the vertical axis can also affect the amount of frictional force that causes the spring retaining element 7442b to deflect laterally, thereby releasing the second spring 7128. By contacting the spring retaining element 7442b, the second spring 7128 can exert a force on the spring retaining element 7442b at a distance d from the bottom of the spring retaining element 7442b, generating a torque moment sufficient to cause the lateral deflection of the spring retaining element 7442b.

[0277] Figure 75A further illustrates the needle carrier assembly 7108, which includes a deflection element 7522 configured to maintain the spring retaining element 7442b in a lateral orientation once the second spring 7128 first deflects the spring retaining element 7442b and the needle carrier assembly 7108, which has been driven sufficiently in the proximal direction, as is shown in more detail in Figure 75B. The deflection element 7522 prevents the spring retaining element 7442b from contacting the windings of the second spring 7128 while the second spring 7128 is extended, thereby smoothing the operation of the applicator 7100 and preventing the energy released by the second spring 7128 and designed to drive the needle carrier assembly 7128 in the proximal direction from being absorbed by undesirable contact with the spring retaining element 7442b during the release of the second spring 7128.

[0278] In some embodiments, the angle θ of the portion of the spring retaining element 7442b that contacts the second spring 7128 may be substantially 90° (e.g., flat), and the deflection element 7522 may have an inclined or angled surface that contacts the spring retaining element 7442b at the position shown in Figure 75A. In such embodiments, in addition to the above functionality, the deflection element 7522 may be configured to initially deflect the spring retaining element 7442b when the first spring 7112 drives the holder 7124 from the position shown in Figure 75A to the position shown in Figure 75B.

[0279] In some embodiments, the inner housing 7102 may include a projection 7546 extending distally from the inner housing 7102. The projection 7546 may be configured to contact at least one of the spring retaining elements 7442a, 7442b and the backstop features 7444a, 7444b in a pre-actualized state, so as to prevent the spring retaining elements 7442a, 7442b from deflecting laterally until the holder 7124 and needle carrier assembly 7108 have translated distally by at least a predetermined minimum distance. Thus, the projection 7546 may provide a drop protection means to prevent the applicator 7100 from firing prematurely in response to an impact shock from a fall before intentional activation.

[0280] Returning to Figure 74A, the inner housing 7102 may further comprise an engaging element 7448 configured to engage with a projection 7449 of the needle carrier assembly 7108 when the needle carrier assembly 7108 is translated distally beyond a predetermined threshold, thereby preventing the needle carrier assembly 7108 from being translated distally beyond the predetermined threshold. This is thought to ensure the retraction of the needle carrier assembly in the case of air or dry firing when the applicator 7100 is activated in any way when not held against the recipient's skin. In some embodiments, the predetermined threshold may correspond to the distal end of the needle carrier assembly 7108 extending beyond a point proximal to the distal end of the inner housing 7102 to a point substantially coinciding with the distal end of the inner housing 7102, or to a point distal to the distal end of the inner housing 7102. In some embodiments, the engaging element 7448 comprises a hook, a U-shaped structure, a loop, a projection, or any other structure capable of engaging with the projection 7449.

[0281] Figure 74B shows the applicator 7100 after activation at the start of the force retraction feature process at or near the distal insertion position where the cutaneous sensor assembly 360 may be in contact with the recipient's skin. The first spring 7112 drives the holder 7124, needle carrier assembly 7108, needle hub 7150, insertion element, and cutaneous sensor assembly 360 distally toward the distal insertion position. During proper operation, the holder 7124 and cutaneous sensor assembly 360 must be pressed against the recipient's skin. However, Figure 74B may also show a dry firing condition where the applicator 7100 is not properly pressed against the recipient's skin before triggering the applicator 7100. Therefore, when the first spring 7112 drives the holder 7124 and the needle carrier assembly 7108 distally beyond a predetermined threshold, the engaging element 7448 contacts the projection 7449, thereby preventing the needle carrier assembly 7108 from moving further distally, while the holder 7124 is driven distally sufficiently such that the backstop features 7444a, 7444b of the needle carrier assembly 7108 no longer contact the spring retaining elements 7442a, 7442b at the distal insertion position, thereby releasing the first end of the second spring 7128 and initiating retraction even when the applicator 7100 is dry-fired. The insertion force provided by the first spring 7112 may be sufficient to further overcome the frictional force between the corresponding contact surface of the backstop feature 7444b and the spring retaining element 7442b.

[0282] Referring to Figure 75B, the first spring 7112 drives the holder 7124, needle carrier assembly 7108, and on-skin sensor assembly 360 distally to the recipient's skin. When the first spring 7112 drives the holder 7124, needle carrier assembly 7108, and on-skin sensor assembly 360 toward the recipient's skin, the skin provides a force to counteract the force generated by the first spring 7112. The skin can counteract the force of the first spring 7112 and bias toward the distal end of the on-skin sensor assembly 360. Since the distal end of the holder 7124 is offset from the distal end of the on-skin sensor assembly 360 as shown in Figure 75A, the reaction force provided by the skin is transferred to the holder 7124 while the first spring 7112 continues to drive the holder 7124 toward the skin, while the on-skin sensor assembly 360 is pressed against the skin. The reaction force provided by the skin allows the spring retaining element 7442b to displace beyond the backstop feature 7444b. When the spring retaining element 7442b exceeds a distance α beyond the backstop feature 7444b, the second spring 7128 deflects the spring retaining element 7442b laterally, thereby releasing the second spring 7128 and driving the needle carrier assembly 7108 proximal. Alternatively, as described above in relation to Figure 75A, if the angle θ of the portion of the spring retaining element 7442b in contact with the second spring 7128 is substantially 90° (e.g., flat), the inclined or angular surface of the deflection element 7522 in contact with the spring retaining element 7444b sufficiently deflects the spring retaining element 7442b, releasing the second spring 7128, which drives the needle carrier assembly 7108 proximal.

[0283] In some embodiments, the engaging element 7448 can engage with the projection 7449 even when the applicator 7100 is pressed against the user's skin. In such embodiments, the engaging element 7448 engages with the projection 7449 when the first spring 7112 drives the holder 7124, the needle carrier assembly 7108, and the skin sensor assembly 360 against the recipient's skin. As described above, the engaging element 7448 prevents the needle carrier assembly 7108 from moving distally when the engaging element 7448 engages with the projection 7449. This allows the spring retaining elements 7442a, 7442b to separate from the backstop features 7444a, 7444b and to release the second spring 7128. The engagement between the engaging element 7448 and the projection 7449 can add an additional force to the reaction force provided by the skin, thereby increasing the energy required to overcome the frictional engagement of the spring retaining elements 7442a, 7442b and the backstop features 7444a, 7444b. In some examples, the engagement between the engaging element 7448 and the projection 7449 provides an immediate impact force that converts at least a portion of the initial energy of the first spring 7112 into the energy required to overcome the frictional engagement of the spring retaining elements 7442a, 7442b and the backstop features 7444a, 7444b. Such embodiments are thought to be beneficial for users with soft skin or a higher body fat percentage.

[0284] Returning to Figure 74C, which shows the applicator 7100 in operation, the needle carrier assembly 7108 is retracted proximally by the second spring 7128, as indicated by arrow 7402. In Figure 74C, the backstop features 7444a and 7444b do not fix the spring retaining elements 7442a and 7442b. Therefore, the first end of the second spring 7128 presses against the spring retaining elements 7442a and 7442b with sufficient force to deflect them to the distal insertion position when the skin assembly 360 contacts the recipient's skin 130. This allows the second spring 7128 to clear the spring retaining elements 7442a and 7442b and drive the needle carrier assembly 7108 proximal, thereby maintaining the needle carrier assembly 7108, the needle hub 7150 (see Figures 73A-73C), and the insertion element 7174 (see Figures 73A-73C) in a locked retracted position, even in the case of dry firing.

[0285] Figures 76A and 76B show enlarged views of some feature parts of an applicator, such as applicator 7100, according to several embodiments.

[0286] In Figure 76A, the first spring 7112 (see Figures 72-74C) drives the holder 7124, as well as the distal needle carrier assembly and cutaneous sensor assembly 360, indicated by arrow 7602, toward the distal insertion position. The retaining element 7372b of the needle carrier assembly is releasably coupled to the cutaneous sensor assembly 360. As shown, during insertion and near the distal insertion position, the holder 7124 contacts the spring retaining element 7372b, preventing the spring retaining element 7372b from deflecting laterally, thereby firmly securing the cutaneous sensor assembly 360 to the needle carrier assembly.

[0287] In Figure 76B, the second spring 7128 (see Figures 72-74C) drives the needle carrier assembly 7108 proximal from the distal insertion position. Because the holder 7124 is sufficiently driven distally, at the distal insertion position, the holder 7124 is no longer in contact with the wearable retaining element 7372b. Thus, the wearable retaining element 7372b is free to deflect laterally, thereby freeing the on-skin sensor assembly 360 from the wearable retaining element 7372b and therefore from the needle carrier assembly 7108. Here, the needle carrier assembly 7108 is driven proximal by the second spring 7128, while the on-skin sensor assembly 360 is fixed to the recipient's skin. Furthermore, in some embodiments, the holder 7124 is driven to a distal insertion position and substantially held in that position by a first spring 7112 so that the holder 7124 can press against one or both of the cutaneous sensor assembly 360 or the adhesive patch of the cutaneous sensor assembly 360 and support one or both during attachment to the recipient's skin.

[0288] Figure 90 shows enlarged views of some feature parts of the applicator of Figures 71 and 72 according to several embodiments. As shown, the applicator 7100 is in a pre-operation state. In this state, the spring retaining elements 7442a, 7442b can be retained against the backstop feature parts 7444a, 7444b. The second spring 7128 can bias the spring retaining elements 7442a, 7442b against the backstop feature parts 7444a, 7444b. As described above, sufficient force is required to deflect the spring retaining elements 7442a, 7442b past the backstop feature parts 7444a, 7444b. Sufficient force can be determined, or at least partially determined, by the frictional force between the spring retaining elements 7442a, 7442b and the backstop feature parts 7444a, 7444b. It can be understood that the backstop features 7444a and 7444b may feature grooves 7446a and 7446b, respectively, for engagement with the spring retaining elements 7442a and 7442b. The grooves 7446a and 7446b may increase the resistance between the spring retaining elements 7442a and 7442b and the backstop features 7444a and 7444b. In such embodiments, the grooves 7446a and 7446b may increase the force required to deflect the spring retaining elements 7442a and 7442b away from the backstop features 7444a and 7444b, while the material of the spring retaining elements 7442a and 7442b and / or the backstop features 7444a and 7444b may have a low or lower coefficient of friction. Furthermore, the grooves 7446a and 7446b can increase the force required to deflect the spring retaining elements 7442a and 7442b away from the backstop features 7444a and 7444b, while the second spring 7128 has a smaller or smaller diameter, or a lower or lower spring constant. In some embodiments, the grooves 7446a and 7446b may each feature a concave channel. The concave shape of the channel may feature an angled surface configured to resist multiple edges of the spring retaining elements 7442a and 7442b. In such embodiments, the spring retaining elements 7442a and 7442b may be wedges configured to resist within the grooves 7446a and 7446b.In some embodiments, the applicator 7100 may include the same number of grooves 7446 as the backstop feature 7444.

[0289] Figure 77 shows a partial perspective cross-sectional view of the needle carrier assembly 7108, needle hub 7150, and skin sensor assembly 360 of the applicator 7100 of Figures 71 and 72, according to several embodiments. Figure 78 shows a cross-sectional view of the needle hub 7150 and skin sensor assembly 360, according to several embodiments. Figure 79 shows a top view of a portion of the needle carrier assembly 7108 and needle hub 7150, according to several embodiments. The following is a description of these features with reference to Figures 77 to 79.

[0290] The skin sensor assembly 360 includes a sensor assembly opening 396. The hub 7150 is configured to connect the insertion element 7174 to the needle carrier assembly 7108 and to substantially maintain the desired orientation of the insertion element 7174 while inserting the sensor of the skin sensor assembly 360 into the recipient's skin.

[0291] The needle hub 7150 comprises a plurality of upper arms 7156a, 7156b, a plurality of lower arms 7154a, 7154b, and a base 7152. Although two upper arms and two lower arms are shown, any number of arms, including a single upper arm and a single lower arm, is conceivable. In some embodiments, the upper arms 7156a, 7156b and the lower arms 7154a, 7154b may be flexible so that when the needle hub 7150 is coupled to the needle carrier assembly 7108, the upper arms 7156a, 7156b and the lower arms 7154a, 7154b secure the needle hub 7150 in a desired orientation relative to the needle carrier assembly 7108. For example, the upper arms 7156a, 7156b may be configured to bend radially inward so that, when positioned through the carrier opening 7712 of the needle carrier assembly 7108, the upper arms 7156a, 7156b contact the upper surface of the needle carrier assembly 7108 adjacent to the carrier opening 7712, and the lower arms 7154a, 7154b contact the lower surface of the needle carrier assembly 7108 adjacent to the carrier opening 7712. Such a configuration allows for a adaptive mating between the needle carrier assembly 7108 and the needle hub 7150, and allows the lower arms 7154a, 7154b to deflect and clear the surface of the carrier opening 7712, after which the upper arms 7156a, 7156b extend. The lower arms 7154a, 7154b can partially or completely slacken to bias the needle hub distally, reducing the clearance between the needle hub and the needle carrier that would otherwise exist in a mismatched mating. In addition, the upper arms 7156a, 7156b and the lower arms 7154a, 7154b also help maintain contact between the base 7152 and the top surface of the skin sensor assembly 360.

[0292] The base 7152 includes an anti-rotation feature. The anti-rotation feature may include a key having a shape that complements at least a portion of the sensor assembly opening 396 of the skin sensor assembly 360, and may be configured to substantially prevent the needle hub 7150 from rotating with respect to the skin sensor assembly 360 about an axis 7702 parallel to the insertion element 7174, for example, by preventing rotation of the base 7152 within the sensor assembly opening 396. Furthermore, or alternatively, the upper surface of the needle carrier assembly 7108 adjacent to the carrier opening 7712 may include a groove 7910 configured to receive the upper arms 7156a, 7156b when the upper arms 7156a, 7156b are positioned through the carrier opening 7712 in an orientation complementary to the orientation of the groove 7910, as shown in Figure 79, thereby securing the needle hub 7150 to the needle carrier assembly 7108.

[0293] In some embodiments, the base 7152 further includes a substantially flat surface configured to engage with the top surface of the skin sensor assembly 360 and maintain the insertion element 7174 in an orientation substantially perpendicular to the top surface of the skin sensor assembly 360 when the anti-rotation feature of the base 7152 is engaged within the sensor assembly opening 396 of the skin sensor assembly 360.

[0294] Based on at least the above-described features of the needle hub 7150, the skin sensor assembly 360, and / or the needle carrier assembly 7108, the base 7152 enables easy assembly during manufacturing, including, but not limited to, the ability to properly align and pre-assemble the insertion element 7174 onto the skin sensor assembly 360, and / or to easily engage the assembly of the needle hub 7150, the insertion element 7174, the sensor 338, and the skin sensor assembly 360 with other parts of the assembled applicator 7100.

[0295] Figures 80A and 80B show perspective views of the locking features of needles 8074a and 8074b for use in an applicator of an analyte sensor system, according to several embodiments. For example, needle 8074a in Figure 80A includes a locking feature comprising a ridge 8076 configured to mate with a complementary shaped feature within, for example, the needle hub 7150. Alternatively, needle 8074b in Figure 80B includes a locking feature comprising a groove 8078 configured to mate with a complementary shaped feature within, for example, the needle hub 7150.

[0296] In yet another alternative embodiment, any insertion element described herein may include, for example, a locking feature that heat-stakes the selected insertion element to the needle hub 7150. In yet another alternative embodiment, any insertion element described herein may include a locking feature that includes, for example, one or more friction-fit or snap-fit ​​elements that secure the selected insertion element to the needle hub 7150. In yet another alternative embodiment, any insertion element described herein may include a locking feature that includes, for example, a complementary clamshell element on the selected insertion element and the needle hub 7150 configured to mate with each other, for example. In yet another alternative embodiment, any insertion element described herein may include a locking element that includes, for example, one or more insertion-molding elements configured to couple the selected insertion element to the needle hub 7150.

[0297] During manufacturing, the applicator 7100 may be assembled in stages. For example, if present, a first barrier layer 7192 may be attached to the inner housing 7102. The insertion element 7174 may be coupled to the needle hub 7150, which may then be coupled to the skin sensor assembly 360. The second spring 7128 may be placed in the holder 7124 or the needle carrier assembly 7108, which may then be placed in the holder 7124 and attached to the needle hub 7150 and the skin sensor assembly 360 via wearable retaining elements 7372a, 7372b. The first spring 7112 may be placed in the holder 7124, which may then be placed in the inner housing 7102. The inner housing 7102 may be inserted into and secured to the outer housing 7102. If present, the second barrier layer 7194 may be attached to the inner housing 7102. If they are separate elements, the actuation element 7104 may then be disposed in the outer housing 7101. Any labeling, sterilization, and / or packaging may then be applied to the applicator 7100.

[0298] Figures 81A to 81C show several cross-sectional views of yet another applicator 8100 for a skin sensor assembly of an analyte sensor system according to several embodiments, as well as various feature parts and operating positions.

[0299] The applicator 8100 may include an outer applicator housing 7101 comprising an actuation element 7104. The outer applicator housing 7101 is configured to translate distally under force applied by the applicator 8100's receiver, thereby aligning the actuation element 7104 to a position that allows the applicator 8100 to launch, the alignment shown in Figure 81A. As previously described in relation to the applicator 7100, in some embodiments the actuation element 7104 may be located at any position, for example, on the top, top, bottom, or any other position of the applicator 8100.

[0300] The applicator 8100 further comprises an inner housing 7102 configured to house one or more mechanisms used to apply the skin sensor assembly 360 to the skin of an recipient. The distal surface 7130 of the bottom opening of the inner housing 7102 may define the bottom surface of the applicator 8100. In some embodiments, when the applicator 8100 is pressed against the skin of an recipient, the skin deforms substantially convexly at the distal surface 7130, thereby causing at least a portion of the skin surface positioned at the bottom opening of the applicator housing 7102 to extend proximal to the bottom opening of the inner housing 7102 beyond the plane defined by the distal surface 7130.

[0301] Although not shown in Figures 81A to 81C, the inner housing 7102 may include a spring 7320 configured to contact the outer housing 7101 and maintain a predetermined distance between the outer housing 7101 and the inner housing 7102 in a pre-actual orientation (see Figure 73A). The spring 7320 may be a compression spring, a leaf spring, a bend-arm spring, foam, or rubber, etc. In some other embodiments, the outer housing 7101 may also include a spring 7320, which may be configured to contact the inner housing 7102.

[0302] The applicator 8100 may further comprise a needle carrier assembly 8108. The needle carrier assembly 8108 comprises a plurality of wearable retaining elements and / or alignment elements 7372a, 7372b configured to pass through the holder 8124 and releasably couple the on-skin sensor assembly 360 to the holder 8124 and / or the needle carrier assembly 8108. Although two wearable retaining elements and / or alignment elements are shown, any number of wearable retaining elements and / or alignment elements are possible.

[0303] The applicator 8100 further comprises a needle hub 7150 configured to connect an insertion element 7174 to a needle carrier assembly 8108. The insertion element 7174 is configured to insert the sensor 338 of the surface sensor assembly 360 into the skin 130 of the recipient (e.g., Figures 3A-4). In some embodiments, the insertion element 7174 comprises a needle, e.g., a single-ended needle, a needle with a deflected tip, a curved needle, a polymer-coated needle, a subcutaneous injection needle, or any other suitable type of needle or structure, as described at least in relation to Figures 47-50 and 80A-80B. In yet another embodiment, the insertion element 7174 may be formed integrally with the sensor 338, and the insertion element 7174 may be rigid enough to be partially inserted into the skin 130 of the recipient with minimal or no structural support.

[0304] The applicator 8100 is releasably coupled to the needle carrier assembly 8108 and may further include a holder 8124 configured to guide the supraskin sensor assembly 360 while coupled to the needle carrier assembly 8108, for example, during translation from at least a proximal position to a distal insertion position. As previously described in relation to the applicator 7100, the supraskin sensor assembly 360 may be detached or released from the holder 8124 and / or the needle carrier assembly 8108 once the supraskin sensor assembly 360 is placed on the skin of the recipient.

[0305] The applicator 8100 may further comprise an insertion assembly configured to translate the insertion element 7174, the needle hub 7150, and the needle carrier assembly 8108 from a proximal position to a distal insertion position. Such an insertion assembly may include a first spring 7112. The first spring 7112 may be a compression spring or any preferred type of spring and may have a first end in contact with or coupled to the inner applicator housing 7102 and a second end in contact with or coupled to the holder 8124. The first spring 7112 is configured, upon operation of the insertion assembly, to translate the holder 8124, the needle carrier assembly 8108, the needle hub 7150, the insertion element 7174, and the cutaneous sensor assembly 360 distally to a distal insertion position. At the substantially distal insertion position, the needle carrier assembly 8108 can be detached from the holder 8124 and the cutaneous sensor assembly 360.

[0306] The applicator 8100 may further include a retraction assembly configured to translate the needle carrier assembly 8108, the needle hub 7150, and the insertion element 7174 in the proximal direction from the distal insertion position to the 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 a second spring 8128. The second spring 8128 may be a compression spring or any preferred type of spring and may have a first end that contacts or connects to the holder 8124 and a second end that includes a tongue 8129 (e.g., a spring portion or spring end) disposed substantially along the diameter of the second spring 8128 and contacts or connects to the spring retaining element 8142 of the holder 8124 at least until retraction. The spring retaining element 8142 may include, for example, an arm, a deflection element, a tab, a stopper, a snap, or any other feature capable of retaining. The spring retaining element 8142 may have substantially the same form and function as the spring retaining elements 7442a and 7442b of the applicator 7100, except as described below. The second spring 8128 is configured to translate the needle carrier assembly 8108, the needle hub 7150, and the insertion element 7174 in the proximal direction from the distal insertion position to the proximal retraction position. The tongue 8129 of the second spring 8128 is released from the spring retaining element 8142 in the distal insertion position when the spring retaining element 8142 is not backed up by the backstop element 8144, and in response to the tongue 8129 of the second spring 8128 pressing against the spring retaining element 8142 with a force exceeding a predetermined threshold sufficient to overcome and deflect the spring retaining element 8142.

[0307] In some embodiments, movement of the on-skin sensor assembly 360 between insertion and withdrawal may occur, for example, as described above in relation to any of Figures 35A to 37C.

[0308] The needle carrier assembly 8108 further comprises a backstop feature 8144 configured to prevent lateral movement of the spring retaining element 8142 of the holder 8124, at least in the pre-proximal operating position, thereby supporting the retention of the second spring 8128 between the spring retaining element 8142 and the holder 8124 until it is retracted. In the orientation shown in Figure 81A, the second spring 8128 is exerting force on the spring retaining element 8142, but the backstop feature 8144 prevents lateral deflection of the retaining element 8142.

[0309] The holder 8124 further comprises a needle carrier retaining element 7334, which may include a deflectable arm, a rigid arm, a deformable feature, a snap, a catch, or a hook. When the needle carrier assembly 8108 reaches the proximal retracted position after operation, the needle carrier retaining element 7334 engages with the needle carrier assembly 8108, thereby maintaining the needle carrier assembly 8108, the needle hub 7150, and the insertion element 7174 in a locked retracted position, and restricting access to the insertion element 7174.

[0310] Although not shown in Figures 81A to 81C, the inner housing 7102 of the applicator 8100 may further comprise an engaging element 7448, and the needle carrier assembly 8108 may further comprise a projection 7449, which may function substantially as described above, at least in relation to Figures 74A to 74C.

[0311] Although not shown in Figures 81A to 81C, the inner housing 7102 of the applicator 8100 may further include a projection extending distally from the inner housing 7102, substantially similar to the projection 7546 described above. Similar to that described above in relation to Figure 75A, this projection may be configured to contact at least one of the spring retaining element 8142 and the backstop feature 8144 in the pre-actual state so as to prevent the spring retaining element 8142 from deflecting laterally until the holder 8124 and the needle carrier assembly 8108 have translated distally by at least a predetermined minimum distance. Thus, the projection may provide a drop protection means to prevent the applicator 8100 from firing prematurely in response to an impact shock from a fall before activation.

[0312] Applicator 8100 functions substantially the same as applicator 7100, except that applicator 8100 utilizes a spring retaining element 8142 that is disposed along the inside of the second spring 8128 and configured to contact and retain the tongue 8129 of the second spring 8128 along the diameter of the second spring 8128, rather than utilizing spring retaining elements 7442a, 7442b that are disposed along the outside of the second coil 7128 and configured to contact and retain the coil of the second spring 7128. By disposing the spring retaining element 8142 along the inside and substantially center of the second spring 8128 rather than along the outside of the second spring 8128, it is further ensured that the spring retaining element 8142 does not contact the coil of the second spring 8128 when the second spring 8128 is extended during retraction, thereby smoothing the operation of applicator 8100. In addition, in contrast to the spring retaining elements 7442a and 7442b, the configuration including the spring retaining element 8142 reduces the risks and difficulties in ensuring that multiple spring retaining elements are triggered or overcome substantially simultaneously.

[0313] Although not shown in Figures 81A–81C, in some embodiments the applicator 8100 may be configured to be fixed to the distal surface 7130 of the inner housing 7102 and may include a cap that can be removed before use. In some embodiments, such a cap may also function as a sterile barrier, as described in U.S. Patent Application No. 16 / 011527, which is incorporated herein in its entirety by reference.

[0314] Figure 81A shows the state of the applicator 8100 before operation in several embodiments. The holder 8124, needle carrier assembly 8108, needle hub 7150, insertion element 7174, skin sensor assembly 360, first spring 7112, and second spring 7128 are all shown in the pre-operation position.

[0315] The retaining element 7332 of the holder 8124 contacts the inner housing 7102, thereby securing the holder 8124, and thus fixing the needle carrier assembly 8108, needle hub 7150, insertion element 7174, and skin sensor assembly 360 in their pre-operation state.

[0316] The backstop feature 8144 of the needle carrier assembly 8108 contacts the spring retaining element 8142, preventing it from deflecting laterally, thereby ensuring that the spring retaining element 8142 securely holds the tongue 8129 of the second spring 8128 in the indicated load or pre-operation position.

[0317] The operation of the applicator 8100 may include the recipient pressing the applicator 8100 against the skin with sufficient force to cause the outer housing 7101 to distally translate relative to the inner housing 7102 until the actuation element 7104 aligns with the insertion assembly retaining element 7332 of the holder 8124, as shown in Figure 81A. Once such alignment is achieved, the recipient can initiate the actuation element 7104, thereby deflecting the insertion assembly retaining element 7332 sufficiently to release the holder 8124 from the inner housing 7102. In some other embodiments, the applicator 8100 may be configured such that the actuation element 7104 is initially actuated, but actual insertion is not triggered until the outer housing 7101 has sufficiently distally translated relative to the inner housing 7102. In yet another embodiment, the actuation element 7104 may be biased toward the center of the applicator 8100 so that it is not necessary for the actuation element 7104 to be explicitly actuated by the recipient. Alternatively, the actuation element 7104 may be configured to automatically begin insertion when the outer housing 7101 has been sufficiently translated distally relative to the inner housing 7102.

[0318] Figure 81B shows the applicator 8100 after activation and during insertion according to several embodiments. The first spring 7112 drives the holder 8124, needle carrier assembly 8108, needle hub 7150, insertion element 7174, and supraskin sensor assembly 360 distally toward the distal insertion position. Figure 81B shows the supraskin sensor assembly 360 in contact with the recipient's skin 130, although the holder 8124 is not yet fully driven by the first spring 7112 to contact the supraskin sensor assembly 360 or the recipient's skin 130.

[0319] In some embodiments, the masses of the holder 8124, needle carrier assembly 8108, needle hub 7150, insertion element 7174, and skin sensor assembly 360 may be specifically designed to reduce or substantially eliminate the tendency for the needle carrier assembly 8108, needle hub 7150, insertion element 7174, and skin sensor assembly 360 to detach from the holder 8124 while they are driven distally during insertion. In some embodiments, the force exerted by the first spring 7112 may be further selected to be sufficient for the proper operation of the applicator 7100, but not so large as to further exacerbate the inertially triggered detachment described above. In some embodiments, a spring (not shown) may be configured to apply a force sufficient to prevent the needle carrier assembly 7108 from being inertially triggered to detach from the holder 8124 during insertion, for example, distally to a portion of the needle carrier assembly 8108.

[0320] Figure 81C shows the applicator 8100 after activation and at or near the distal insertion position according to several embodiments. A first spring 7112 drives the holder 8124, the needle carrier assembly 8108, and the skin sensor assembly 360 distally to the distal insertion position. Because the first spring 7112 drives the holder 8124 a shorter distance distal to the needle carrier assembly 8108, the backstop feature 8144 no longer contacts the spring retaining element 8142, and a second spring 8128 (e.g., tongue 8129) can deflect the spring retaining element 8142 laterally, thereby releasing the second spring 8128 which drives the needle carrier assembly 8108 proximal. Alternatively, as described above in relation to the applicator 7100 in Figure 75A, if the angle θ of the portion of the spring retaining element 8142 that contacts the tongue 8129 of the second spring 7128 is substantially 90° (e.g., flat), the spring retaining element 8142 is biased to automatically deflect sufficiently to release the second spring 7128 when the backstop feature 8144 is no longer in contact with the spring retaining element 8142, thereby releasing the second spring 8128 and driving the needle carrier assembly 8108 in the proximal direction. Although not shown in Figures 81A to 81C, the inner housing 7102 may further include an engaging element 7448 that engages with a projection 7449 of the needle carrier assembly 8108 and is configured to function substantially as described above, at least in relation to Figures 74A to 74C. In some embodiments, a stopping feature (not shown) may be located at the bottom of the applicator 8100, for example, in the distal portion of the inner housing 7102. Such a stopping feature may be configured to contact one or more of the supracutaneous sensor assembly 360, the needle carrier 8108, or the holder 8124 at the distal insertion position.

[0321] When the second spring 8128 is released, it is configured to drive the needle carrier assembly 8108, the needle hub 7150, and the insertion element 7174 in the proximal direction. Although not shown in Figure 81C, when the needle carrier assembly 8108 moves to the proximal retracted position, the needle carrier retaining element 7134 engages with the needle carrier assembly 8108, thereby holding the needle carrier assembly 8108, the needle hub 7150, and the insertion element 7174 in a locked retracted position, restricting access to the insertion element 7174.

[0322] Figure 81D shows perspective views of the holder 8124, the first spring 7112, and the second spring 8128 of the applicator 8100 according to several embodiments. Figure 81D shows the spring retaining element 8142 and the retaining tongue 8129 of the second spring 8128 in orientation within the applicator 8100 before retraction.

[0323] During manufacturing, the applicator 8100 may be assembled in stages. For example, if present, a first barrier layer 7192 (see Figure 72) may be attached to the inner housing 7102, as previously described in relation to the applicator 7100, though not limited to this. The insertion element 7174 may be coupled to the needle hub 7150, which may then be coupled to the skin sensor assembly 360. A second spring may be placed in the holder 8124 or the needle carrier assembly 8108, which may then be placed in the holder 8124 and attached to the needle hub 7150 and the skin sensor assembly via wearable retaining elements 7372a, 7372b. The first spring 7112 may be placed in the holder 8124, which may then be placed in the inner housing 7102. The inner housing 7102 may be inserted into and secured to the outer housing 7102. If present, a second barrier layer 7194 (see Figure 72) can be attached to the inner housing 7102, as previously described in relation to the applicator 7100. If a separate element, the actuation element 7104 may then be disposed in the outer housing 7101. Any labeling, sterilization, and / or packaging may then be applied to the applicator 8100.

[0324] Figures 82A to 82D show several cross-sectional views of yet another applicator 8200 for a skin sensor assembly of an analyte sensor system, according to several embodiments, as well as various feature parts and operating positions. In contrast to applicators 7100 and 8100, applicator 8200 utilizes a single spring for both the insertion and retraction of the insertion element 8274 for positioning the associated sensor 338 and skin sensor assembly 360.

[0325] The applicator 8200 comprises a housing 8202 and an actuation element 8204 disposed on the top of the applicator 8200. However, the actuation element 8204 may be disposed on the side of the applicator 8200 or at any other location.

[0326] The applicator 8200 may further comprise a needle carrier assembly 8208. The needle carrier assembly 8208 comprises a plurality of wearable retaining elements and / or alignment elements 8272a, 8272b configured to pass through the holder 8224 and releasably couple the on-skin sensor assembly 360 to the holder 8224 and / or the needle carrier assembly 8208. In some embodiments, the wearable retaining elements 8272a, 8272b may extend around the holder 8224 rather than passing through it. The wearable retaining elements 8272a, 8272b may comprise, for example, arms, deflection elements, tabs, stoppers, snaps, or any other feature parts capable of retaining function. Although two wearable retaining elements and / or alignment elements are shown, any number of wearable retaining elements and / or alignment elements are conceivable. The needle carrier assembly 8208 further includes a projection 8266 configured to contact or hook onto the deployment sleeve 8206 during retraction, thereby translating the needle carrier assembly 8208 in the proximal direction during retraction, as will be described in more detail below.

[0327] The applicator 8200 further comprises an insertion element 8274 configured to insert the sensor 338 of the skin sensor assembly 360 into the skin 130 of the recipient (e.g., Figure 1). In some embodiments, the insertion element 8274 comprises a needle, e.g., a single-opening needle, a needle with a deflected tip, a curved needle, a polymer-coated needle, a subcutaneous injection needle, or any other suitable type of needle or structure, as described at least in relation to Figures 47-50 and 80A-80B. In yet another embodiment, the insertion element 8274 may comprise a sensor 338 that is rigid enough to be partially inserted into the skin 130 of the recipient with minimal or no structural support.

[0328] Although not shown in Figures 82A to 82D, in some embodiments the applicator 8200 may further include a needle hub 7150 configured to couple the insertion element 8274 to the needle carrier assembly 8208, as described above at least in relation to Figures 77 to 79. In some other embodiments, the insertion element 8274 may be coupled directly to the needle carrier assembly 8208, as shown in Figures 82A to 82D.

[0329] The applicator 8200 may further include a holder 8224 releasably coupled to the deployment sleeve 8206 and to the needle carrier assembly 8208 via holder retaining elements 8232a, 8232b. The holder retaining elements 8232a, 8232b may comprise, for example, arms, deflection elements, tabs, return mechanisms, snaps, or any other features capable of retaining functions. The holder 8224 is configured to guide the cutaneous sensor assembly 360 while coupled to the needle carrier assembly 8208 during insertion, for example, during translation from at least the proximal position to the distal insertion position. As previously described in relation to applicators 7100 and 8100, the cutaneous sensor assembly 360 may be detached or released from the holder 8224 and / or the needle carrier assembly 8208 once the cutaneous sensor assembly 360 is placed on the recipient's skin.

[0330] The applicator 8200 may further comprise an insertion assembly configured to translate the holder 8224, the insertion element 8274, and the needle carrier assembly 8208 distally from a proximal position to a distal insertion position. Such an insertion assembly may include a spring 8212. The first spring 8212 may be a compression spring or any preferred type of spring and may have a first end in contact with or coupled to the deployment sleeve 8206 and a second end in contact with or coupled to the holder 8224. The first spring 8212 is configured, upon operation of the insertion assembly, to translate the holder 8224, the needle carrier assembly 8208, the insertion element 8274, and the cutaneous sensor assembly 360 distally to a distal insertion position. At substantially the distal insertion position, the needle carrier assembly 8208 can be detached from the holder 8224 and the cutaneous sensor assembly 360.

[0331] The applicator 8200 may further include a retraction assembly configured to translate the needle carrier assembly 8208 and the insertion element 8274 in the proximal direction from the distal insertion position to the 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 also include a spring 8212. The first spring 8212 is also configured to translate the deployment sleeve 8206, the needle carrier assembly 8208, and the insertion element 8274 in the proximal direction from the distal insertion position to the proximal retraction position in response to the on-skin sensor assembly 360 making contact with the recipient's skin 130 and / or reaching the limit of movement with a force exceeding a predetermined threshold. For example, although not shown, the housing 8202 may further include an engagement element 7448 that engages with a projection 7449 of the needle carrier assembly 8208 and is configured to function substantially as described above, at least in relation to Figures 74A-74C. In some embodiments, a stopping...

Claims

1. A needle hub and a skin sensor assembly, wherein the needle hub is configured to apply the skin sensor assembly to the skin of a recipient, and the needle hub is A base (7172) equipped with an anti-rotation mechanism, wherein the base (7172) is configured to be at least partially positioned in the opening (396) of the skin sensor assembly (360), The opening (396) is adapted for the insertion of a sensor and a needle. The needle hub is configured to be coupled with the insertion element (7174), The anti-rotation mechanism is configured to prevent the base (7172) from rotating within the opening (396) of the needle hub and skin sensor assembly.

2. The anti-rotation mechanism comprises a key having a shape that complements at least a portion of the opening, as described in claim 1, for the needle hub and skin sensor assembly.

3. The needle hub and skin sensor assembly according to claim 1, further comprising at least one upper arm.

4. The needle hub and skin sensor assembly according to claim 3, wherein the at least one upper arm is configured to be positioned through an opening in the needle carrier assembly of the applicator.

5. The needle hub and skin sensor assembly according to claim 4, wherein the at least one upper arm is configured to contact the upper surface of the needle carrier assembly adjacent to the opening of the needle carrier assembly.

6. The needle hub and skin sensor assembly according to claim 5, wherein the at least one upper arm is configured to be positioned in a groove on the upper surface of the needle carrier assembly, thereby securing the needle hub to the needle carrier assembly.

7. The needle hub and skin sensor assembly according to claim 3, wherein at least one upper arm is flexible.

8. The needle hub and skin sensor assembly according to claim 3, wherein at least one upper arm is configured to bend radially inward.

9. The needle hub and skin sensor assembly according to claim 3, further comprising at least one lower arm.

10. The needle hub and skin sensor assembly according to claim 9, wherein the at least one lower arm is configured to contact the lower surface of the needle carrier assembly adjacent to the opening in the needle carrier assembly.

11. The needle hub and skin sensor assembly according to claim 1, wherein the insertion element includes a needle.

12. The needle hub and skin sensor assembly according to claim 11, wherein the needle has an open side configured to receive the sensor of the skin sensor assembly.

13. The needle hub and skin sensor assembly according to claim 1, wherein the base comprises a flat surface configured to engage with the top surface of the skin sensor assembly, thereby maintaining the insertion element in an orientation substantially perpendicular to the top surface of the skin sensor assembly.

14. The aforementioned insertion element (7174) is A locking mechanism including a ridge configured to engage with a complementary shaped feature portion within the needle hub, A locking mechanism including a groove configured to engage with a complementary shaped feature portion within the needle hub, A locking mechanism for thermally fixing the insertion element to the needle hub, A locking element including one or more friction-fit or snap-fit ​​elements for securing the insertion element to the needle hub, A locking mechanism including the insertion element and a complementary clamshell element configured to fit together on the needle hub, or A locking element including one or more insertable molded elements configured to connect the insertable element to the needle hub, The needle hub and skin sensor assembly according to claim 1, comprising:

15. The needle hub and skin sensor assembly according to claim 1, wherein the skin sensor assembly (360) comprises an electronic unit.

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