Submicron particle deposition in pulmonary alveoli during cyclic breathing

The prediction of deposition eciency of submicron particles in the pulmonary alveoli has received special attention due to its importance for drug delivery systems and for assessing air pollutants health risks. In this work, the pulmonary alveoli of a healthy human are idealized by a three-dimensional honeycomb-like conguration and a  fluid-structure interaction analysis is performed. In contrast to previous works in which the inlet ow rate is predened, in this model, a negative pressure is imposed on the outside surface of the alveolus which causes air to  flow in and out of the alveolus. The resulting flow patterns conrmed that there was no circulation in the terminal alveolus. The predicted alveolar air flow was used to calculate the trajectories of submicron particles using the Lagrangian approach. Our ndings suggest that an accurate simulation requires including at least ten breathing cycles, considering a parabolic radial distribution of injected particles andcontinuous injection. The presented results show high deposition eciency for submicron sizes in the alveolar region if these particles can reach the alveolar region. Therefore, the vesicles technology in which particle agglomerates would be released after the vesicle reaching the alveoli is suggested for targeted drug delivery to the alveolar region.