Transport and targeting of pulmonary inhalation aerosols: mechanistic lessons from the deep lungs

Mapping respiratory airflows and the transport mechanisms of inhaled aerosols characteristic of the deep regions of the lungs are of broad interest in assessing inhalation therapy outcomes. In the present talk, I will discuss our current understanding of such phenomena characterized by sub-millimeter 3D alveolated airspaces and low-Reynolds-number flows. I will exemplify advances brought forward by experimental efforts, in conjunction with numerical simulations, to revisit past mechanistic theories of respiratory airflow and particle transport, emphasizing the coupled roles of convection, diffusion, sedimentation and most recently electrostatics. I will highlight how microfluidics spanning the past decade have accelerated opportunities to deliver anatomically-inspired models that capture with sufficient realism and accuracy the leading mechanisms governing respiratory airflow and aerosol transport at true scale. Such efforts have provided previously unattainable in vitro quantifications on the local transport properties in the deep pulmonary acinar airways, with new paths to resolve mechanistic interactions between airborne particulate carriers and respiratory airflows at the pulmonary microscales.