This experimental investigation was undertaken to quantify the electrostatic charge and aerodynamic size distribution of the medicinal drug particles inhaled through an in-vitro mouth-throat (MT) in order to compare the amount of drugs can be delivered to the human lung while mimicking a patient is either sitting or lying. The MT model is a cadaver-based replica cast of human oral-pharyngeal-laryngeal region. Tested drug aerosols were generated by a commercially available metered dose inhaler (MDI). The MT model was placed inside a humidity (95%) and temperature (37oC) controlled chamber. Its mouth-inlet was positioned horizontally and vertically to simulate sitting and lying administration, respectively. The laryngeal-exit was connected to the aerosol sampling chamber (ASC) and the ASC was also connected with an electronic single particle relaxation time analyzer (ESPARTA). In each run, the ASC was cleaned and evacuated down to 36 cm of mercury so that a bolus of 4 liters of aerosol could be drawn at a rate of 30 L/min for a period of 8 seconds. Aerosols were generated from a single puff (for each run) into a spacer (Valve Holding Chamber), and instantly inhaled through the MT as bolus. Once the ASC was filled after 8 seconds of inhalation, the valve between the ASC and the ESPARTA was shut and a circulating fan was started instantly. Then the ESPARTA was started characterizing aerosol particles’ aerodynamic diameter and electrostatic charge simultaneously in real time. The results show that deposition of total (charged and uncharged) particles in the MT was double for lying position compared to sitting, which can be explained by inertial impaction of the oral jet at the bend of oral cavity, and gravitational settling of the pharyngeal and laryngeal jets when flowing horizontally through these two regions. Whereas, charged particles deposition was ten folds for lying compared to sitting. In this case, an effect of electrostatic image charge force on particle deposition efficiency can explain the outcome. In addition, particle deposition in the sitting position did not suffer gravitational settling rather it helped aerosols to move faster beyond larynx.


Association of Technology, Management and Applied Engineering 2022 Annual Conference

Date of publication

Fall 11-10-2022



Persistent identifier


Document Type

Conference Proceeding