Suppression of short-range exposure to infectious aerosols using multiple paths of midair ultrasound acoustic streaming

Abstract

One of the major infectious routes of respiratory diseases, such as COVID-19, is exposure to viral aerosols transmitted from an infected person over a short distance. Conventionally, plastic shields or personalized ventilation methods utilizing fans or jets to generate airflows between two facing users have been used to combat such short-range infection. Nevertheless, these methods entail several drawbacks: bulky apparatus hindering users’ cooperative activities must be placed between them, the shields need frequent cleaning and block conversation voices, and the jet- or fan-based methods yield uncomfortably strong airflows hitting the user’s face. Here, a new airflow-based strategy for suppressing aerosol exposure, which overcomes all the above inconveniences, was proposed. In this strategy, ultrasound-driven localized airflows called acoustic streaming, whose positions and traveling directions can be electronically controlled, was used. A prototype system composed of a group of phased arrays of airborne ultrasound transducers was created, and they were set behind the users to redirect paths of aerosols emitted from the user’s mouth toward their upper and back sides. It is experimentally confirmed that the proposed system could reduce exposure to aerosols whose diameters are the same as ones emitted from people by 89.95% under a certain setup. By controlling the position and direction of the streaming, the proposed method can maintain its performance when users move their heads or bodies. The proposed system can virtually produce or delete programmable partitions in the air as desired, and can be integrated with other conventional methods for infection control.

Graphical Abstract

Editor:

• Se-Jin Yook

Acknowledgments

The authors thank Prof. Takaaki Nara and Dr. Hiroki Miyazako for their helpful comments and advice throughout this study. The authors also thank Dr. Hitoshi Oshitani for providing insightful comments regarding this study.

Disclosure statement

The contact author has declared that none of the authors have competing interests.

Additional information

Funding

This study was supported by JST, PRESTO Grant No. JPMJPR21R9, Japan.