A Novel Approach for Measuring Deposition Characteristics of Nebulized Droplets using a Realistic Mouth-Throat Airway Model

Hao Xu, Huizhen Yang, XIAOLE CHEN, Ya Zhang, Yu Feng, Nanjing Normal University

     Abstract Number: 175
     Working Group: Health-Related Aerosols

Abstract
Deposition experiments were conducted to investigate the behavior of nebulized droplets in a realistic mouth-throat airway model. The droplets were generated using a customized vibrating mesh nebulizer. The median mass aerodynamic diameter (MMAD) and geometric standard deviation (GSD) of the nebulized droplets were measured as 5.019 μm and 1.495, respectively. The droplet solution consisted of fluorescent normal saline. The mouth-throat airway model was reconstructed based on a CT scan of a healthy 46-year-old male. The deposition characteristics of the nebulized droplets, including deposition fractions and patterns, were examined under five different inhalation flow rate conditions.

The deposition fraction decreased from 27.06% at 15 L/min to 17.91% at 22.5 L/min, and then gradually increased to 33.85%, 42.03%, and 61.92% at flow rates of 30, 45, and 60 L/min, respectively. These findings generally align with our previous experiments using an idealized mouth-throat model (Yang et al., 2023). However, the deposition fractions observed in our study were higher than those reported in the idealized mouth-throat model proposed by Zhang et al. (2006).

As the flow rate increased, the deposition pattern of the fluorescent droplets demonstrated a gradual transition from the oral cavity to the posterior region of the oropharynx. Our novel method enabled quantitative determination of the deposition fraction and qualitative visualization of the droplet deposition pattern in a single experiment.

References
[1] Yang, Huizhen, et al. "The effects of temperature and humidity on the deposition of nebulized droplet in an idealized mouth-throat model." Flow Measurement and Instrumentation 91 (2023): 102359.
[2] Zhang, Yu, Tze Luck Chia, and Warren H. Finlay. "Experimental measurement and numerical study of particle deposition in highly idealized mouth-throat models." Aerosol Science and Technology 40.5 (2006): 361-372.