Transcutaneous analyte sensors, applicators therefor, and associated methods
The present embodiments relate generally to applicators of on-skin sensor assemblies for measuring an analyte in a host, as well as their method of use and manufacture. In some aspects, an applicator for applying an on-skin sensor assembly to a skin of a host is provided. The applicator includes an applicator housing, a needle carrier assembly comprising an insertion element configured to insert a sensor of the on-skin sensor assembly into the skin of the host, a holder releasably coupled to the needle carrier assembly and configured to guide the on-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.
1. An applicator for applying an on-skin sensor assembly to a skin of a host, the applicator comprising:
an insertion assembly configured to translate a needle carrier assembly and the on-skin sensor assembly in a distal direction from an initial proximal position to a distal insertion position;
an inner housing;
an outer housing comprising an activation element configured to activate the insertion assembly, wherein the activation element is prevented from activating the insertion assembly until the outer housing is translated a predetermined distance in a distal direction with respect to the inner housing; and
a retraction assembly configured to translate the needle carrier assembly in a proximal direction from the distal inserted position to a proximal retracted position, wherein the retraction assembly is configured to activate when the on-skin sensor assembly contacts the skin of the host.
2. The applicator of claim 1 , wherein the insertion assembly comprises a first spring.
3. The applicator of claim 2 , wherein the retraction assembly comprises a second spring.
4. The applicator of claim 3 , wherein the insertion assembly further comprises a holder configured to guide the needle carrier assembly at least during translation from the initial proximal position to the distal insertion position.
5. The applicator of claim 4 , wherein the holder further comprises at least one retention element configured to retain the second spring at least during insertion.
6. The applicator of claim 5 , wherein the needle carrier assembly further comprises at least one backstop feature configured to prevent lateral deflection of the at least one retention element at least during insertion.
7. The applicator of claim 6 , wherein the at least one backstop feature is configured not to contact the at least one retention element in the distal insertion position, thereby allowing the second spring to deflect the at least one retention element and activate the retraction assembly.
8. The applicator of claim 5 , wherein the second spring is configured to exert a force sufficient to deflect the at least one retention element in the distal insertion position when the on-skin sensor assembly is in contact with the skin of the host.
9. The applicator of claim 1 , wherein the inner housing further comprises an engagement element and the needle carrier assembly comprises a protrusion, the engagement element configured to engage with the protrusion upon the needle carrier assembly translating in a distal direction beyond a predetermined threshold, thereby preventing the needle carrier assembly from translating in the distal direction beyond the predetermined threshold.
10. The applicator of claim 9 , wherein the engagement element comprises a hook.
11. The applicator of claim 1 , wherein the activation element is disposed on a side of the outer housing.
12. The applicator of claim 11 , wherein the activation element is configured to be pushed in a lateral direction towards an interior of the outer housing.
13. The applicator of claim 1 , wherein
the inner housing includes an aperture, and
the activation element is configured to be aligned with the aperture when the outer housing is translated the predetermined distance in the distal direction with respect to the inner housing.
14. A method for applying an on-skin sensor assembly to skin of a host, the method comprising:
providing an applicator comprising:
an inner housing,
an outer housing comprising an activation element,
an insertion assembly, and
a retraction assembly; and
activating the activation element, wherein activating the activation element includes translating the outer housing a predetermined distance in a distal direction with respect to the inner housing, wherein activating the activation element causes:
the insertion assembly to translate a needle carrier assembly and the on-skin sensor assembly in a distal direction from a proximal position to a distal insertion position, thereby inserting a sensor of the on-skin sensor assembly at least partially into the skin of the host; and
the retraction assembly to translate the needle carrier assembly in a proximal direction from the distal inserted position to a proximal retracted position, the retraction assembly configured to activate when the on-skin sensor assembly contacts the skin of the host.
15. The method of claim 14 , wherein the insertion assembly comprises a first spring and a second spring.
16. The method of claim 14 , wherein the insertion assembly further comprises a holder configured to guide the needle carrier assembly at least during translation from the proximal position to the distal insertion position.
17. The method of claim 16 , wherein the holder further comprises at least one retention element configured to retain the second spring at least during insertion.
18. The method of claim 17 , wherein the needle carrier assembly further comprises at least one backstop feature configured to prevent lateral deflection of the at least one retention element at least during insertion.
19. The method of claim 18 , wherein the at least one backstop feature is configured not to contact the at least one retention element in the distal insertion position, thereby allowing the second spring to deflect the at least one retention element and activate the retraction assembly.
20. The method of claim 18 , wherein the second spring is configured to exert a force sufficient to deflect the at least one retention element in the distal insertion position when the on-skin sensor assembly is in contact with the skin of the host.
21. The method of claim 14 , wherein the inner housing further comprises an engagement element and the needle carrier assembly comprises a protrusion, the engagement element configured to engage with the protrusion upon the needle carrier assembly translating in a distal direction beyond a predetermined threshold, thereby preventing the needle carrier assembly from translating in the distal direction beyond the predetermined threshold.
22. The method of claim 21 , wherein the engagement feature comprises a hook.
23. The method of claim 14 , wherein the activation element is disposed on a side of the outer housing.
24. The method of claim 23 , wherein activating the activation element includes pushing the activation element in a lateral direction towards an interior of the outer housing after translating the outer housing the predetermined distance in the distal direction with respect to the inner housing.
25. The method of claim 14 , wherein
the inner housing includes an aperture, and
the activation element is configured to be aligned with the aperture when the outer housing is translated the predetermined distance in the distal direction with respect to the inner housing.