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US-12619025-B2 - Side-emitting optical fibers with surface modification

US12619025B2US 12619025 B2US12619025 B2US 12619025B2US-12619025-B2

Abstract

A modified side-emitting optical fiber includes a core comprising an optical fiber and a UV-C transparent polymer coating over the core. An average surface roughness of the UV-C transparent polymer coating is in a range of about 0.3 μm to about 0.7 μm as measured by root mean square of distance difference measurements of the surface of the UV-C transparent polymer coating. Fabricating a modified side-emitting optical fiber includes contacting a coated optical fiber with a solvent, wherein the coated optical fiber comprises a UV-C transparent polymer coating, and dissolving at least a portion of the UV-C transparent polymer coating in the solvent to yield the modified side-emitting optical fiber, wherein an average surface roughness of the UV-C transparent polymer coating is in a range of about 0.3 μm to about 0.7 μm.

Inventors

  • Paul K. Westerhoff
  • Zhe Zhao
  • Nora Shapiro

Assignees

  • ARIZONA BOARD OF REGENTS ON BEHALF OF ARIZONA STATE UNIVERSITY

Dates

Publication Date
20260505
Application Date
20250307

Claims (20)

  1. 1 . A coated side-emitting optical fiber comprising: a core comprising an optical fiber; and a UV-C transparent polymer coating directly contacting the core and comprising a roughened surface formed by roughening, wherein an average surface roughness of the UV-C transparent polymer coating is in a range of about 0.35 μm to about 0.5 μm as measured by root mean square of distance difference measurements of the surface of the UV-C transparent polymer coating, and a thickness of the UV-C transparent polymer coating before roughening is in a range of about 5 μm to about 50 μm, and wherein the coated side-emitting optical fiber, when inserted in a 1-meter-long pipeline with two 180° bends, each having a bend diameter of 10 cm, emits no more side-emitted light at the bends than along straight sections of the coated side-emitting optical fiber, based on light measurements taken through 3 cm holes located every 10 cm length along the pipeline.
  2. 2 . The coated side-emitting optical fiber of claim 1 , wherein the optical fiber comprises glass or quartz.
  3. 3 . The coated side-emitting optical fiber of claim 1 , wherein the optical fiber has a diameter in a range of about 125 μm to about 1500 μm.
  4. 4 . The coated side-emitting optical fiber of claim 1 , wherein the optical fiber has a refractive index in a range of about 1.4 to about 1.6.
  5. 5 . The coated side-emitting optical fiber of claim 1 , wherein the optical fiber has a numerical aperture in a range of about 0.1 to about 0.5.
  6. 6 . The coated side-emitting optical fiber of claim 1 , wherein the UV-C transparent polymer coating comprises a fluorinated polymer.
  7. 7 . The coated side-emitting optical fiber of claim 1 , wherein the UV-C transparent polymer coating comprises nanoparticles with a diameter in a range of about 100 nm to about 500 nm.
  8. 8 . The coated side-emitting optical fiber of claim 7 , wherein the nanoparticles comprise silicon, silica oxide, gold, silver, other metals, or other metal oxides.
  9. 9 . The coated side-emitting optical fiber of claim 8 , wherein the nanoparticles are functionalized with aminated organic compounds, carboxylated organic compounds, or neutral organic ligands.
  10. 10 . A method of fabricating a modified side-emitting optical fiber, the comprising: coating an optical fiber with a UV-C transparent polymer coating to yield a coated optical fiber, wherein a thickness of the UV-C transparent polymer coating is in a range of about 5 μm to about 50 μm; contacting the coated optical fiber with a solvent; and dissolving at least a portion of the UV-C transparent polymer coating in the solvent to yield a roughened UV-C transparent polymer coating on the optical fiber, wherein an average surface roughness of the roughened UV-C transparent polymer coating is in a range of about 0.35 μm to about 0.5 μm as measured by root mean square of distance difference measurements of the surface of the roughened UV-C transparent polymer coating, wherein the optical fiber with the roughened UV-C transparent polymer coating, when inserted in a 1-meter-long pipeline with two 180° bends, each having a bend diameter of 10 cm, emits no more side-emitted light at the bends than along straight sections of the side-emitting optical fiber, based on light measurements taken through 3 cm holes located every 10 cm length along the pipeline.
  11. 11 . The method of claim 10 , wherein the solvent comprises an organic solvent.
  12. 12 . The method of claim 11 , wherein the organic solvent comprises a fluorinated organic solvent.
  13. 13 . The method of claim 12 , wherein the fluorinated organic solvent comprises perfluorotributylamine.
  14. 14 . The coated side-emitting optical fiber of claim 1 , wherein the UV-C transparent polymer coating is free of nanoparticles.
  15. 15 . The coated side-emitting optical fiber of claim 1 , wherein a tensile strength of the coated side-emitting optical fiber is in a range of 540 to 650 MPa.
  16. 16 . The coated side-emitting optical fiber of claim 1 , wherein side emission of the coated side-emitting optical fiber is at least 5 times higher at any place along the UV-C transparent polymer coating after roughening than at any place along the UV-C transparent polymer coating before roughening.
  17. 17 . The method of claim 10 , wherein side emission of the coated optical fiber with the roughened UV-C transparent polymer coating is at least 5 times higher at any place along the coated side-emitting optical fiber than at any place along the coated optical fiber before the dissolving.
  18. 18 . The method of claim 10 , wherein coating the optical fiber comprises providing the optical fiber to an optical fiber draw tower.
  19. 19 . The method of claim 10 , wherein contacting the coated optical fiber with the solvent occurs for a length of time between about 1 hour and about 3 hours.
  20. 20 . The method of claim 10 , wherein the UV-C transparent polymer coating is free of nanoparticles.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/US2023/079309, filed on Nov. 10, 2023, which claims the benefit of U.S. Patent Application No. 63/424,195 filed on Nov. 10, 2022, both of which are incorporated by reference herein in their entirety. STATEMENT OF GOVERNMENT SUPPORT This invention was made with government support under 1449500 awarded by National Science Foundation and under 80NSSC21C0034 awarded by the National Aeronautical & Space Administration. The government has certain rights in the invention. TECHNICAL FIELD This invention relates to side-emitting optical fibers with modified surfaces for use in germicidal UV-C disinfection. BACKGROUND Germicidal ultraviolet-C (UV-C) disinfection is a widely used technology that is commonly accomplished using mercury lamps, which have several disadvantages. Light emitting diodes (LEDs) are mercury-free, and advances over the past decade have improved their efficiencies in the UV-C ranges. The current limitation of LEDs is their relatively small and limited area of irradiation per chip, which limit the area or zone in which LEDs can disinfect microorganisms in water or surface biofilms. SUMMARY A low-cost and tunable manufacturing method is described to enable side-emission of germicidal light from flexible glass optical fibers with a core diameter in range of about 125 μm to about 1500 μm with an ultraviolet-C (UV-C) transparent polymer coating into air or water along the length of the fiber. Optical fibers that emit light along the length of the fiber are made by partially dissolving away a UV-C transparent polymer coating covering the optical fiber core. The partial dissolution of the polymer coating creates a textured or roughened surface which facilitates side-emission of light out of the core of the optical fiber. The optical fiber design facilitates the use of UV-LED based light for disinfection, oxidation, or other purposes. The size and flexibility of the side-emitting optical fiber (SEOF) allows germicidal UV-C irradiation in difficult to reach areas where microbial proliferation often occurs. Although the disclosed inventive concepts include those defined in the attached claims, it should be understood that the inventive concepts can also be defined in accordance with the following embodiments. Embodiment 1 is a modified side-emitting optical fiber comprising: a core comprising an optical fiber; anda UV-C transparent polymer coating over the core,wherein an average surface roughness of the UV-C transparent polymer coating is in a range of about 0.3 μm to about 0.7 μm as measured by root mean square of distance difference measurements of the surface of the UV-C transparent polymer coating. Embodiment 2 is the modified side-emitting optical fiber of embodiment 1, wherein the optical fiber comprises glass or quartz. Embodiment 3 is the modified side-emitting optical fiber of embodiment 1 or 2, wherein the core has a diameter in a range of about 125 μm to about 1500 μm. Embodiment 4 is the modified side-emitting optical fiber of any one of embodiments 1-3, wherein the optical fiber has a refractive index in a range of about 1.4 to about 1.6. Embodiment 5 is the modified side-emitting optical fiber of any one of embodiments 1-4, wherein the optical fiber has a numerical aperture in a range of about 0.1 to about 0.5. Embodiment 6 is the modified side-emitting optical fiber of any one of embodiments 1-5, wherein the thickness of the UV-C transparent polymer coating before modification is in a range of about 5 μm to about 50 μm. Embodiment 7 is the modified side-emitting optical fiber of any one of embodiments 1-6 wherein the UV-C transparent polymer coating comprises a fluorinated polymer. Embodiment 8 is the modified side-emitting optical fiber of any one of embodiments 1-7, wherein the UV-C transparent polymer coating comprises nanoparticles with a diameter in a range of about 100 nm to about 500 nm. Embodiment 9 is the modified side-emitting optical fiber of embodiment 8, wherein the nanoparticles comprise silicon, silica oxide, gold, silver, other metals, or other metal oxides. Embodiment 10 is the modified side-emitting optical fiber of embodiment 9, wherein the nanoparticles are functionalized with aminated organic compounds, carboxylated organic compounds, or neutral organic ligands. Embodiment 11 is a method of fabricating a modified side-emitting optical fiber, the method comprising: contacting a coated optical fiber with a solvent, wherein the coated optical fiber comprises a UV-C transparent polymer coating; anddissolving at least a portion of the UV-C transparent polymer coating in the solvent to yield the modified side-emitting optical fiber, wherein an average surface roughness of the UV-C transparent polymer coating is in a range of about 0.3 μm to about 0.7 μm. Embodiment 12 is the method of embodiment 11, wherein the average surface roughness corresponds to a root mean sq