UV-plasmonic germicidal radiation beams enabled by sonoluminescence of air bubbles near liquid-metal particles

The UV-C band ultraviolet light irradiation is one of the most commonly used ways of disinfecting water contaminated by pathogens such as bacteria and viruses. Sonoluminescence, the emission of light from acoustically-induced collapse of air bubbles in water, is an efficient means of generating UV-C light. However, because a spherical bubble collapsing in the bulk of water creates isotropic radiation, the fluence of the generated UV-C radiation is insufficient for disinfection. Here, we theoretically demonstrate that we can create a UV light beam from aspherical air bubble collapse near a gallium-based liquid-metal microparticle. The beam is perpendicular to the metal surface and is caused by the interaction of sonoluminescence light with UV plasmon modes in the metal. We calculate that such beams are capable of generating UV-C fluences exceeding 10mJ/cm2, which is sufficient to irreversibly inactivate 99.9% of pathogens in water with the turbidity of more than 5NTU.