Medical optical fiber with a protective tip and method for manufacturing the same

Abstract

The present invention relates to a medical optical fiber having a protective tip for use with an endoscope in laser-based treatment of visceral organs and a method for manufacturing the same. The medical optical fiber has a short stripped medical optical fiber portion and a protective tip provided thereon to encapsulate the stripped medical optical fiber portion and the sheath tip immediately following it.

Description

Field of the Invention

[0001] The present invention relates to a medical optical fiber for an endoscope for laser treatment of internal organs and a method for manufacturing the same. Background of the Invention

[0003] Medical optical fibers include a concentric arrangement of optical fibers and a sheath surrounding the optical fibers. The optical fiber includes an innermost optical core and at least one transparent cladding layer (hereinafter referred to as "cladding layer") surrounding the optical core. The cladding layer must have a refractive index lower than that of the optical core. The optical fiber optionally includes at least one mechanical support layer (hereinafter referred to as "mechanical support layer") surrounding the cladding layer. Medical optical fibers can be stripped of the sheath like electrical wires, leaving a stripped medical optical fiber segment or a bare optical fiber segment. The diameter of medical optical fibers ranges from several tens of micrometers to several hundreds of micrometers. Therefore, the distal tip of medical optical fibers is often very sharp.

[0004] The light energy generated by a medical laser is usually transmitted to the target tissue through a medical optical fiber. Aiming at internal body organs usually requires an endoscope. Passing a medical optical fiber through an endoscope can be problematic and even cause perforation. During operation, depending on the laser energy transmitted, the erosion rate of the fiber tip may be faster than that of the sheath tip, which can cause the fiber tip to sink relative to the sheath tip, which is not conducive to continued operation. In a liquid environment, the optical fiber is affected by cavitation forces, resulting in corrosion. The effects of cavitation forces on different concentric layers of medical optical fibers are different.

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

[0006] U.S. Patent No. 9,031,370 jointly owned by Khachaturov relates to a medical optical fiber having a sheath that is slotted towards its sheath tip, and when the distal optical core end corrodes, the sheath peels off in a controlled manner rather than in a random manner.

[0007] There is a need for a medical optical fiber with a tip that assists it in passing through an endoscope to reach the target tissue in an internal body organ 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 making the same. The protective tip of the present invention is similar to the above-mentioned tip attachment in assisting the passage of the medical optical fiber through an endoscope, and is designed to shatter, break, melt or otherwise destroy when a laser pulse is emitted to expose at least one optical core end face, thereby delivering laser energy to an organ in the body. However, unlike the above-mentioned tip attachment, 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. Therefore, the protective tip of the present invention overlaps the sheath material at the sheath tip. In addition, the protective tip of the present invention protects the sheath tip from the effects of the collapse of cavitation bubbles, thereby protecting the optical fiber tip. Therefore, 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, and the like. 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 help provide 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 hole 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 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] FIG. 1 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 3Longitudinal 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 Longitudinal cross-sectional view of a medical optical fiber including a slotted sheath tip and a protective tip according to a third embodiment of the present invention;

[0015] Figure 5 is Figure 4 Cross-sectional view of the medical optical fiber along line A-A; and

[0016] Figures 6A to 6D Shows a method of manufacturing a medical optical fiber with a protective tip according to the present invention. Detailed Description

[0017] Medical optical fiber with a protective tip

[0018] FIG. 1 shows a medical optical fiber 10 having a longitudinal medical optical fiber axis 11 and a tip attachment 12 according to commonly owned U.S. Patent No. 9,968,404. The medical optical fiber 10 includes a coaxial optical fiber 13 and a sheath 14 surrounding the optical fiber 13. The optical fiber 13 includes an innermost core 16, a cladding 17 surrounding the core 16, and a mechanical support layer 18 surrounding the cladding 17. The optical fiber 13 has a distal optical fiber tip 19 having an optical fiber end face 21 transverse to the longitudinal medical optical fiber axis 11. The sheath 14 has a distal sheath tip 22 having a sheath end face 23 transverse to the longitudinal medical optical fiber axis 11.

[0019] The medical optical fiber 10 has a stripped medical optical fiber portion 24 extending from the tail surface 26 of the tip attachment to the sheath end face 23. The stripped medical optical fiber portion 24 has a length L1 in the range of 50 - 2,000 microns along the longitudinal medical optical fiber axis 11. The sheath 14 has an outer maximum dimension D1. The tip attachment 12 is cured on the optical fiber tip 19 and encapsulates the optical fiber end face 21 therein. The tip attachment 12 has a maximum outer dimension D2 transverse to the longitudinal medical optical fiber axis 11, where D2 > D1. The D2 of the tip attachment is less than the working channel of the endoscope inner diameter for passage.

[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 outer 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 outer 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 polymer 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 prerequisite is that the melting temperature of the polymer material of the sheath is T1 and the curing temperature of the polymer material of the protective tip is T2, where T2 < T1 to avoid melting of the sheath. Preferably, T2 / T1 ≥ 1.1. Depending on the polymer 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 Medical optical fiber 50A similar to medical optical fiber 30 is shown, and thus similar components are numbered the same. Medical optical fiber 50 differs from medical optical fiber 30 in that the sheath 33 has at least one hole formed by one or more grooves 51 transverse to the longitudinal medical optical fiber axis 31 to expose the mechanical support layer 37 therefrom. Thus, the installation of the protective tip 44 on the optical fiber 50A causes the protective tip material to contact the mechanical support layer 37 or the cladding 36 through the grooves 51. The contact of the protective tip material on the mechanical support layer 37 has a greater adhesion strength than the contact on the sheath 33. The grooves 51 can be made deeper so that they expose the cladding 36.

[0025] Figure 4 and Figure 5 Medical optical fiber 50B is shown, which is similar to medical optical fiber 50A but differs in the aperture for exposing the cladding 36 or the mechanical support layer 37. Medical optical fiber 50B includes a groove 52 coaxial with the longitudinal medical optical fiber axis 31. The groove 52 optionally extends from the sheath end face 42.

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

[0027] Now refer to Figures 6A to 6D A method for manufacturing the medical optical fiber 50A is described, which includes the following steps:

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

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

[0030] Step 3: Form a groove 72 in the sheath 63 toward the sheath end face 69 to expose the mechanical support layer 67. The groove can be deepened to expose the cladding 66.

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

[0032] Step 5: Provide a protective tip 73 on the medical optical fiber 60 to encapsulate the fiber end face 68 and the sheath end face 69. The protective tip 73 has a front protective tip surface 74 in front of the fiber end face 68. The protective tip 73 has a tail protective tip surface 76 that is spaced from the sheath end face 69 along the longitudinal medical fiber axis 61 by a length L3 measured from the fiber end face 68, where L3 is in the region of 450 ± 50 μm.

[0033] Although the invention has been described with respect to a limited number of embodiments, it should be understood that many 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, which is used for treating human organs based on laser, the medical optical fiber comprising: An optical fiber having a distal optical fiber tip, the distal optical fiber tip having an optical fiber end face transverse to the longitudinal axis of the medical optical fiber, the optical fiber including an innermost optical core having an optical core; 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 axis, the sheath tip having an outer maximum dimension D1, the sheath end face including a recessed portion proximal to the distal optical fiber tip at the distal end of the optical fiber, the recessed portion including a length L, where L is greater than or equal to 200 micrometers (μm) and less than or equal to 500 μm; and A protective tip that encapsulates the optical fiber end face and the sheath end face therein and has a maximum outer dimension D2 transverse to the longitudinal axis, where D2 is greater than D1, The protective tip has a front protective tip surface located in front of the optical fiber end face and a tail protective tip surface separated from the sheath end face along the longitudinal axis, whereby the protective tip encapsulates the recessed portion of the distal optical fiber tip and overlaps the sheath tip between the sheath end face and the tail protective tip surface, The tail protective tip includes a length extending proximally from the optical fiber end face, the length being greater than or equal to 500 μm and less than or equal to 1100 μm, and The protective tip is made of a material that fractures or melts upon incidence of laser energy to enable the laser energy to be transmitted through the optical core end face to an internal body organ.

2. The optical fiber according to claim 1, wherein the sheath is made of a polymer material with a melting temperature of T1, and the protective tip is made of a polymer material with a curing temperature of T2, where T2 < T1.

3. The optical fiber according to any one of claims 1 - 2, wherein the recessed portion exposes a stripped portion of the medical optical fiber, and the peripheral surface of the stripped portion of the medical optical fiber is treated to assist in providing the protective tip.

4. The optical fiber according to any one of claims 1 - 2, wherein the sheath tip forms at least one hole for exposing the optical fiber layer below the sheath tip, such that the protective tip contacts the underlying layer through the at least one hole.

5. The optical fiber according to claim 4, wherein one of the at least one holes is coaxial with the longitudinal axis of the medical optical fiber.

6. The optical fiber according to claim 5, wherein the hole extends along the end face of the sheath.

7. The optical fiber according to claim 4, wherein one of the at least one holes is transverse to the longitudinal axis of the medical optical fiber.

8. 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) Provide a medical optical fiber having a longitudinal axis, the medical optical fiber having: i) A distal optical fiber end and an innermost optical core having an optical core end face at the center of the optical fiber end face, and ii) A sheath surrounding the optical fiber, the sheath having a distal sheath tip having a sheath end face transverse to the longitudinal axis, The distal sheath tip has an outer maximum dimension D1, The sheath end face includes a recessed portion proximal to the distal optical fiber tip at the distal end of the optical fiber, the recessed portion including a length L, where L is greater than or equal to 200 micrometers (μm) and less than or equal to 500 μm; and (b) Provide a protective tip that encapsulates the optical fiber end face, the sheath end face, and the recessed portion therein and has a maximum outer dimension D2 transverse to the axis, where D2 is greater than D1, The protective tip has a front protective tip surface located in front of the optical fiber end face and a tail protective tip surface separated from the sheath end face along the longitudinal medical optical fiber axis, whereby the protective tip encapsulates the recessed portion of the distal optical fiber tip and overlaps the sheath tip between the sheath end face and the tail protective tip surface, The tail protective tip includes a length extending proximally from the optical fiber end face, the length being greater than or equal to 500 μm and less than or equal to 1100 μm, The protective tip is made of a material that fractures or melts upon incidence of laser energy to enable the laser energy to be transmitted through the optical core end face to an internal body organ.

9. The method according to claim 8, wherein the sheath is made of a polymer material with a melting temperature of T1, and the protective tip is made of a polymer material with a curing temperature of T2, where T2<t1。10. The method according to any one of claims 8 - 9, wherein the peripheral surface of the stripped portion of the medical optical fiber is treated to assist in providing the protective tip.

11. The method according to any one of claims 8 - 9, further comprising step (c): the sheath tip is formed with at least one hole for exposing the fiber layer below the sheath tip such that the protective tip contacts the underlying layer through the at least one hole.

12. The method according to claim 11, wherein step (c) comprises forming a hole coaxial with the longitudinal axis of the medical optical fiber.

13. The method according to claim 12, wherein step (c) comprises forming a hole extending along the end face of the sheath.

14. The method according to claim 11, wherein step (c) comprises forming a hole transverse to the longitudinal axis of the medical optical fiber.

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