Side-Emitting Optical Fibers for Delivery of UV-C Light to Disinfect Key Bacteria in Space Station Water and Storage and Conveyance Systems

Bacteria in water and surface-attached biofilms pose health and operational challenges in human support systems. Current biofilm control technologies (i.e., hydrophobic surfaces, biocide-impregnated plastic coatings, chemical biocides, mercury-based lamps or light emitting diodes (LEDs)) either work for a very short duration, lead to residual chemical by-products of concern, have impractical physical designs, ornbsp;limited light irradiation capacity. We propose a means of increasing the irradiation area of a UV-C LED by gt;100x by launching its light into side-emitting optical fibers (SEOFs), essentially creating germicidal flexible glowsticks. Currently only visible light SEOFs are commercially available. However, we discovered a technology (patent-pending) using silica nanoparticles (NPs) permanently attached to optical fibers that achieve side-emission of UV-C light along the entire optical fiber length. This is achieved using our dual-layer SEOF that includes 1) tunable shape-, size-, and surface chemistry-modified silica NPs that create photon and energy-scattering centers on the fiber surface and 2) UV-C transparent polymer coating over the NPs that protects the SEOF while allowing light to enter the water. Flexible individual or bundled SEOFs can deliver light from UV-C LED(s) to large surface areas. Our SEOF technology targets biofilm control in water or air, including narrow channels in potable water devices or tubing, biomedical devices or surface disinfection. Research performed during the Phase I STTR successfully 1) optimized the SEOF NP coating, 2) advanced development of desirable light profiles along SEOF, 3) developed a proprietary first-principle optical fiber light scattering mathematical model to engineer the SEOF and 4) demonstrated bacterial inactivation in water or on surfaces. This Phase II STTR proposal advances research initiated in Phase I and develops prototype devices for technology demonstration (TRL 5).