Medical optical fiber with protective tip and method

Abstract

Medical optical fibers with protective tips and methods of making the same are disclosed. The invention further relates to a medical optical fiber having a protective tip for use with an endoscope for laser-based visceral organ treatment and to a method for the production thereof. The medical fiber has a short stripped medical fiber portion and a protective tip disposed thereon to enclose the stripped medical fiber portion and a sheath tip immediately thereafter.

Description

[0001] This application is a divisional application of the patent application with application number "201980025770.2", application date "April 18, 2019", and titled "Medical optical fiber with protective tip and manufacturing method thereof". Field of the Invention

[0002] The present invention relates to a medical optical fiber for an endoscope used for laser treatment of internal organs and a method for manufacturing the same. Background of the Invention

[0003] A medical optical fiber comprises a concentric arrangement of optical fibers and a sheath surrounding the optical fibers. The optical fiber comprises an innermost optical core and at least one transparent cladding surrounding the optical core (hereinafter referred to as the "cladding"). The cladding must have a lower refractive index than the optical core. The optical fiber optionally comprises at least one mechanical support layer surrounding the cladding (hereinafter referred to as the "mechanical support layer"). The medical optical fiber can be stripped of its sheath like an electrical wire, leaving a stripped medical optical fiber segment or a bare optical fiber segment. The diameter of a medical optical fiber ranges from tens of microns to hundreds of microns; therefore, the distal tip of a medical optical fiber is often sharp.

[0004] Light energy generated by medical lasers is typically delivered to the target tissue via medical optical fibers. Targeting internal body organs often requires an endoscope. Passing a medical optical fiber through an endoscope can be problematic, even causing perforations. During operation, depending on the delivered laser energy, the fiber tip can erode faster than the sheath tip. This can cause the fiber tip to deflect relative to the sheath tip, hindering continued operation. In a liquid environment, the optical fiber is subject to cavitation forces, which can lead to erosion. Cavitation forces affect the different concentric layers of the medical optical fiber differently.

[0005] U.S. Patent No. 9,968,404, co-owned by Ashraf et al., relates to a medical optical fiber having a smooth tip appendage to assist in passing the medical optical fiber through an endoscope. U.S. Patent No. 9,968,404 discloses providing a smooth tip appendage on the distal tip of a medical optical fiber. The tip appendage is intended to shatter, fragment, melt, or otherwise break when a laser pulse is emitted to expose the optical core. The tip appendage can have a spherical surface, a hemispherical surface, a curved surface, etc. The tip appendage can be formed from a variety of polymer materials, including epoxy resin materials, acrylate materials, UV glue, etc. The tip appendage can be formed on the tip of the optical fiber by known manufacturing techniques, including curing, gluing, etc.

[0006] Commonly owned US Patent No. 9,031,370 to Khachaturov is directed to a medical optical fiber having a jacket that is grooved toward its jacket tip so that when the distal optical core end corrodes, the jacket peels off in a controlled, rather than random, manner.

[0007] There is a need for a medical optical fiber having a tip that facilitates passage through an endoscope to target tissue in internal body organs and provides protection against cavitation forces in a liquid environment. Summary of the Invention

[0008] The present invention relates to a medical optical fiber having a protective tip for use with an endoscope for laser-based treatment of internal organs, and a method for manufacturing the same. The protective tip of the present invention is similar to the aforementioned tip attachments in assisting passage of the medical optical fiber through an endoscope and is designed to shatter, shatter, melt, or otherwise disrupt upon emission of a laser pulse to expose at least one optical core end face, thereby delivering laser energy to an internal organ. However, unlike the aforementioned tip attachments, the medical optical fiber of the present invention has a short, stripped medical optical fiber portion and a protective tip disposed thereon to encapsulate the stripped medical optical fiber portion and the sheath tip immediately thereafter. Thus, the protective tip of the present invention overlaps the sheath material at the sheath tip. Furthermore, the protective tip of the present invention protects the sheath tip from the effects of cavitation bubble collapse, thereby protecting the optical fiber tip. Thus, the protective tip of the present invention provides a smooth passage of the medical optical fiber through the endoscope and protects the optical fiber tip during laser treatment.

[0009] Protective tips can be provided on medical optical fibers using conventional manufacturing techniques that do not affect their structure or operation. Such conventional manufacturing techniques include gluing, curing, etc. Some conventional manufacturing techniques require consideration of the mechanical and chemical properties of the constituent layers of the medical optical fiber. It is best to prepare the medical optical fiber to facilitate providing a protective tip thereon. One possible preparation includes preparing the stripped medical optical fiber portion so that it presents a rough surface. Another possible preparation step includes chemically and / or physically preparing the peripheral surface of the stripped medical optical fiber portion to provide a surface with higher adhesion capabilities. As described above, some medical optical fibers include a mechanical support layer immediately below the sheath. Some sheath materials have low adhesion, such as polytetrafluoroethylene (Teflon). Therefore, one or more through-holes can be formed in the sheath tip to expose the mechanical support layer or cladding. The protective tip contacts the exposed mechanical support layer or cladding through the holes for fixation. These holes can be formed in a variety of shapes and directions. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to understand the invention and to see how it may be carried out in practice, preferred embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings in which like parts are numbered alike, and in which:

[0011] FIG1 is a longitudinal cross-sectional view of a medical optical fiber including a tip appendage according to commonly owned U.S. Patent No. 9,968,404;

[0012] Figure 2 is a longitudinal cross-sectional view of a medical optical fiber including a protective tip according to a first embodiment of the present invention;

[0013] Figure 3 is a longitudinal cross-sectional view of a medical optical fiber including a slotted distal sheath tip and a protective tip according to a second embodiment of the present invention;

[0014] Figure 4 is a longitudinal cross-sectional view of a medical optical fiber including a slotted jacket tip and a protective tip according to a third embodiment of the present invention;

[0015] Figure 5 yes Figure 4 A cross-sectional view of the medical optical fiber along line AA; and

[0016] 6A to 6D A method for manufacturing a medical optical fiber with a protective tip according to the present invention is shown. DETAILED DESCRIPTION

[0017] Medical fiber optic cables with protective tips

[0018] FIG1 illustrates a medical optical fiber 10 having a longitudinal medical optical fiber axis 11 and a tip appendage 12 according to commonly owned U.S. Patent No. 9,968,404. Medical optical fiber 10 includes a coaxial optical fiber 13 and a jacket 14 surrounding optical fiber 13. Optical fiber 13 includes an innermost optical core 16, a cladding 17 surrounding optical core 16, and a mechanical support layer 18 surrounding cladding 17. Optical fiber 13 has a distal optical fiber tip 19 having a fiber end face 21 transverse to longitudinal medical optical fiber axis 11. Jacket 14 has a distal jacket tip 22 having a jacket end face 23 transverse to longitudinal medical optical fiber axis 11.

[0019] The medical fiber 10 has a stripped medical fiber portion 24 extending from the trailing surface 26 of the tip appendage to the jacket end face 23. The stripped medical fiber portion 24 has a length L1 along the longitudinal medical fiber axis 11 in the range of 50-2,000 microns. The jacket 14 has a maximum outer dimension D1. The tip appendage 12 is cured onto the fiber tip 19 and encapsulates the fiber end face 21 therein. The tip appendage 12 has a maximum outer dimension D2 transverse to the longitudinal medical fiber axis 11, where D2>D1. The tip appendage's D2 is smaller than the inner diameter of the working channel of an endoscope to facilitate passage through it.

[0020] Figure 2Shown is a medical optical fiber 30 having a longitudinal medical optical fiber axis 31 and including a concentrically arranged optical fiber 32 and a sheath 33 surrounding the optical fiber 32. The optical fiber 32 includes an innermost optical core 34, a cladding 36 surrounding the optical core 34, and a mechanical support layer 37 surrounding the cladding 36. The optical fiber 32 has a distal optical fiber tip 38 having an optical fiber end face 39 transverse to the longitudinal medical optical fiber axis 31. The optical core 34 has an optical core end face 34A centered on the optical fiber end face 39. The sheath 33 has a sheath tip 41 having a sheath end face 42 transverse to the longitudinal medical optical fiber axis 31. The sheath 33 has an external maximum dimension D1. The medical optical fiber 30 has a stripped medical optical fiber portion 43 extending from the optical fiber end face 39 to the sheath end face 42. The stripped medical optical fiber portion 43 has a length L2 of 350 ± 150 μm, which is measured along the longitudinal medical optical fiber axis 31 from the optical fiber end face 39.

[0021] The medical optical fiber 30 has a protective tip 44 mounted on the optical fiber tip 38 for encapsulating the optical fiber end face 39 and the sheath end face 42. The protective tip 44 has a front protective tip surface 46 in front of the optical fiber end face 39. The protective tip 44 has a tail protective tip surface 47 that is longitudinally spaced from the sheath end face 42 by a length L3 within a region of 800 ± 300 μm measured along the longitudinal medical optical fiber axis 31 from the optical fiber end face 39. Thus, the protective tip 44 encapsulates the stripped medical optical fiber portion 43 and overlaps the sheath tip 41 between the sheath end face 42 and the tail protective tip surface 47. The protective tip 44 has a maximum external dimension D2 transverse to the longitudinal medical optical fiber axis 31, where D2 > D1.

[0022] The protective tip 44 can be made of a curable polymeric material. The curing can be by temperature curing, chemical curing, radiation curing, etc. Radiation curing can include IR curing, UV curing, visible light curing, etc. Suitable protective tip materials include epoxy resins, acrylates, etc. Depending on the selected manufacturing technique, different materials can be used for different sheath / protective tip combinations. In the case of temperature curing, a necessary condition is that the melting temperature of the polymeric material of the sheath is T1 and the curing temperature of the polymeric material of the protective tip is T2, where T2 < T1 to avoid melting of the sheath. Preferably, T2 / T1 ≥ 1.1. Depending on the polymeric material used for the protective tip, the temperature curing of the protective tip can be carried out at room temperature.

[0023] In use, the transmission of laser energy through the medical optical fiber 30 causes at least some of the front protective tip surface 46 in front of the optical fiber end face 39 to fragment or melt, enabling the laser energy to be transmitted through the optical core end face 34A to an internal body organ.

[0024] Figure 3 A medical fiber 50A is shown that is similar to medical fiber 30, and similar components are numbered accordingly. Medical fiber 50 differs from medical fiber 30 in that the jacket 33 has at least one aperture formed by one or more grooves 51 extending transversely to the longitudinal medical fiber axis 31, allowing the mechanical support layer 37 to be exposed therethrough. Thus, installation of the protective tip 44 on the fiber 50A results in the protective tip material contacting the mechanical support layer 37 or cladding 36 through the grooves 51. The contact of the protective tip material on the mechanical support layer 37 has a greater bond strength than the contact on the jacket 33. The grooves 51 can be made deeper so that they expose the cladding 36.

[0025] Figure 4 and Figure 5 A medical fiber 50B is shown that is similar to medical fiber 50A but differs in the aperture thereof for exposing the cladding 36 or mechanical support layer 37. Medical fiber 50B includes a groove 52 oriented in the same direction as the longitudinal medical fiber axis 31. Groove 52 optionally extends from the jacket end face 42.

[0026] Method for manufacturing medical optical fiber with protective tip

[0027] Now refer to 6A to 6D A method of manufacturing a medical optical fiber 50A is described, the method comprising the following steps:

[0028] Step 1: Provide a standard medical optical fiber 60 having a longitudinal medical fiber axis 61. The medical optical fiber 60 includes concentrically arranged optical fibers 62 and a jacket 63 surrounding the optical fibers 62. The optical fibers 62 include an innermost optical core 64, a cladding 66 surrounding the optical core 64, and a mechanical support layer 67 surrounding the cladding 66. The optical fiber 62 has an optical fiber end face 68. The jacket 63 has an outer jacket end face 69 that is flush with the optical fiber end face 68.

[0029] Step 2: Strip the medical fiber 60 to form a stripped medical fiber portion 71. The stripped medical fiber portion 71 has a length L2 of 350±150 μm, which is measured from the fiber end face 68 along the longitudinal medical fiber axis 61.

[0030] Step 3: A groove 72 is formed in the jacket 63 towards the jacket end face 69 to expose the mechanical support layer 67. The groove may be deepened to expose the cladding 66.

[0031] Step 4: Treat the outer peripheral surface of the stripped medical fiber portion 71 with a protective tip 73 to improve adhesion.

[0032] Step 5: A protective tip 73 is provided on the medical fiber 60 to encapsulate the fiber end face 68 and the jacket end face 69. The protective tip 73 has a leading protective tip surface 74 in front of the fiber end face 68. The protective tip 73 has a trailing protective tip surface 76 that is spaced apart from the jacket end face 69 along the longitudinal medical fiber axis 61 by a length L3 measured from the fiber end face 68, wherein L3 is within the region of 450 ± 50 μm.

[0033] While the invention has been described with respect to a limited number of embodiments, it will be appreciated that numerous variations, modifications and other applications of the invention may be made within the scope of the appended claims.

Claims

1. A medical optical fiber for use with an endoscope for laser-based treatment of human organs, the medical optical fiber having a longitudinal medical optical fiber axis, the medical optical fiber comprising: (a) an optical fiber having a distal fiber tip, the fiber tip having a fiber end face transverse to the longitudinal medical fiber axis, the optical fiber including an innermost optical core having an optical core end face centered on the fiber end face; (b) a sheath surrounding the optical fiber, the sheath having a distal sheath tip, the distal sheath tip having a sheath end face transverse to the longitudinal medical optical fiber axis, the sheath tip having a maximum outer dimension D1 transverse to the longitudinal medical optical fiber axis, the sheath end face being recessed relative to the optical fiber end face thereby leaving a stripped medical optical fiber portion; as well as (c) a protective tip encapsulating the optical fiber end face and the jacket end face therein and having an outer maximum dimension D2 transverse to the circumference of the longitudinal medical optical fiber, wherein D2>D1, The protective tip has a leading protective tip surface located forward of the optical fiber end face and a trailing protective tip surface spaced from the jacket end face along the circumference of the longitudinal medical optical fiber, wherein the protective tip encapsulates the stripped medical optical fiber portion and overlaps the jacket tip between the jacket end face and the trailing protective tip surface. The protective tip is made of a material that absorbs laser energy and one or more fragments or melts, wherein transmission of laser energy through the medical optical fiber causes at least some of the front protective tip surface forward of the optical fiber end face to fragment or melt, thereby enabling the laser energy to be transmitted through the optical core end face to internal body organs.

2. The optical fiber according to claim 1, wherein the jacket is made of a polymer material having a melting temperature of T1, and the protective tip is made of a polymer material having a solidification temperature of T2, wherein T2 <T1。 3. The optical fiber of claim 1 or 2, wherein the stripped medical fiber portion has a length L of 350 ± 150 μm as measured from the fiber end face along the longitudinal medical fiber axis.

4. The optical fiber of any one of claims 1-3, wherein the peripheral surface of the stripped medical optical fiber portion is treated to assist in providing the protective tip.

5. The optical fiber according to any one of claims 1 to 4, wherein the jacket tip is formed with at least one hole for exposing the optical fiber layer below the jacket tip, so that the protective tip contacts the underlying layer through the at least one hole.

6. The optical fiber of claim 5, wherein one of the at least one hole is coaxial with the longitudinal medical fiber axis.

7. The optical fiber of claim 6, wherein the hole extends along the jacket end face.

8. The optical fiber of claim 6, wherein one of the at least one hole is transverse to the longitudinal medical fiber axis.

9. A method for manufacturing a medical optical fiber for an endoscope for laser treatment of internal body organs, the method comprising the following steps: (a) Providing a medical optical fiber, the medical optical fiber having a longitudinal medical optical fiber axis, the medical optical fiber having: i) an optical fiber having a distal fiber tip with a fiber end face transverse to the longitudinal medical fiber axis, The optical fiber includes an innermost optical core having an optical core end face centered at the optical fiber end face, and ii) a sheath surrounding the optical fiber, the sheath having a distal sheath tip with a sheath end face transverse to the longitudinal medical optical fiber axis, The sheath tip has an outer maximum dimension D1 transverse to the longitudinal medical optical fiber axis, The jacket end face is recessed relative to the optical fiber end face, thereby leaving a stripped medical optical fiber portion; and (b) providing a protective tip encapsulating the optical fiber end face and the jacket end face therein and having an outer maximum dimension D2 transverse to the longitudinal optical fiber axis, wherein D2>D1, The protective tip has a leading protective tip surface located forward of the optical fiber end face and a trailing protective tip surface spaced from the jacket end face along the circumference of the longitudinal medical optical fiber, wherein the protective tip encapsulates the stripped medical optical fiber portion and overlaps the jacket tip between the jacket end face and the trailing protective tip surface. The protective tip is made of a material that absorbs laser energy and one or more fragments or melts, wherein transmission of laser energy through the medical optical fiber causes at least some of the front protective tip surface forward of the optical fiber end face to fragment or melt, thereby enabling the laser energy to be transmitted through the optical core end face to internal body organs.

10. The method of claim 9, wherein the sheath is made of a polymer material having a melting temperature T1, and the protective tip is made of a polymer material having a solidification temperature T2, wherein T2 <T1。

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