Endoscopic needle stylet with enhanced-flexibility lengths
A single-wire stylet may be constructed as an elongate single-wire, memory-metal alloy body with a generally cylindrical body profile, extending distally from a proximal end terminus, where embodiments include a polymeric distal tip member fixedly attached directly at a distal end of the single-wire body. At least one lengthwise portion of the single-wire body is at least partially in martensitic phase at operating temperatures at and below about 37° C. Where present, the polymeric distal tip member has a generally cylindrical body profile circumferentially bounded by an outer circumference substantially equal to or greater than that of the metal body. The polymeric distal tip member may be overmolded upon a distal-end tip length of an elongate single-wire, memory-metal alloy stylet body, where the distal end and/or discrete intermediate distal-portion length(s) that include martensitic-phase alloy and any polymeric member have greater flexibility than a proximal-most length of the alloy stylet body.
1. A system of an endoscopic needle and stylet configured for use within the endoscopic needle, the stylet comprising:
a proximal end terminus and a distal end terminus;
an elongate single-wire, memory-metal alloy body with a generally cylindrical body profile that is circumferentially bounded by a first outer circumference, the single-wire body extending distally from the proximal end terminus and comprising a shape memory alloy having an austenite finish temperature (A f ) greater than about 37° C.;
a polymeric distal tip member fixedly attached directly at a distal end of the single-wire body so that a lengthwise portion of the single-wire body is disposed within the polymeric distal tip member;
where the polymeric distal tip member has a generally cylindrical body profile circumferentially bounded by a second outer circumference that is substantially equal to or greater than the first outer circumference; and
where, at operating temperatures at and below about 40° C., at least a distal lengthwise portion of the single-wire body
is at least partially in martensitic phase;
is more flexible than a proximal lengthwise portion of the single-wire body; and
is less flexible than a lengthwise portion of the polymeric distal tip member not occupied by the single-wire body.
2. The system of claim 1 , where the polymeric distal tip member is overmolded upon and around a distal terminal-end length of the single-wire body.
3. The system of claim 2 , where the second outer circumference is substantially equal to the first outer circumference, and the longitudinal distal terminal-end length of the single-wire body that is within the polymeric distal tip member comprises a third outer circumference that is less than the first outer circumference and the second outer circumference.
4. The system of claim 3 , where the longitudinal length of the single-wire body that is within the polymeric distal tip member occupies about one-half or less of the longitudinal distal terminal-end length of the polymeric distal tip member.
5. The system of claim 3 , where the third outer circumference is about 65% to about 95% of the second outer circumference.
6. The system of claim 2 , where the second outer circumference is greater than the first outer circumference.
7. The system of claim 2 , where the first outer circumference is about 65% to about 95% of the second outer circumference.
8. The system of claim 2 , where the longitudinal length of the single-wire body that is within the polymeric distal tip member occupies about one-half or less of the longitudinal length of the polymeric distal tip member.
9. The system of claim 1 , where the fixed attachment of the polymeric distal tip member to the single-wire body comprises one or more of overmolding, adhesive, epoxy, friction-fit interface, or any combination thereof.
10. The system of claim 1 , where the combined length of the polymeric distal tip member and the lengthwise portion of the single-wire body in martensitic phase at operating temperatures at and below about 37° C. comprises at least about one-tenth of a complete length of the stylet between its proximal end terminus and distal end terminus.
11. The system of claim 1 , where the combined length of the polymeric distal tip member and the lengthwise portion of the single-wire body in martensitic phase at operating temperatures at and below about 37° C. comprises no more than about one-haft of a complete length of the stylet between its proximal end terminus and distal end terminus.
12. The system of claim 1 , where the length of the polymeric distal tip member comprises
at least about one-half of a complete length of the stylet between its proximal end terminus and distal end terminus, or
no more than about one-half of a complete length of the stylet between its proximal end terminus and distal end terminus.
13. The system of claim 1 , where the distal terminus of the polymeric distal tip member is hemispherical or otherwise rounded.
14. A needle assembly including the system of claim 1 , where the stylet is disposed at least partially through a longitudinal lumen of the endoscopic needle.