Strategy for Overhead Redirection of Exhaled Infectious Aerosols using Upward Upright Acoustic Streaming by Floor-Reflected Ultrasonic Beam

Diseases caused by exposure to airborne infectious aerosols such as COVID-19 are serious threats to humanity. Recently, besides using masks and physical partitions, ultrasound-driven airflow technically known as the acoustic streaming was employed for the purpose of suppressing direct exposure to aerosols exhaled by a facing person. Although this method was proven to be effective, it can only be applied to a situation where two people face each other. To overcome this restriction, we propose and experimentally demonstrate a technique for redirecting the aerosols emitted from people toward the ceiling of the room by vertical upward acoustic streaming. We place phased arrays of airborne ultrasound transducers on the ceiling and emit ultrasound beams that is reflected on the desk or floor surface, which result in an upward ultrasound beam causing the acoustic streaming toward the ceiling. In this study, we experimentally show that our method is expected to simultaneously suppress the short-range exposure to aerosols and expedite discharge of the aerosols from the room by ventilation systems commonly installed in the ceiling.