The multiscale structure of the respiratory organ encompasses a challenging environment to predict the transport and deposition of inhaled aerosols, whether relevant to therapeutic drug delivery or hazardous exposure assessment. While the traditional leading deposition mechanisms, foremost impaction, gravitational settling and diffusion, are generally well understood and extensively studied, the role of electrostatic charge present in aerosols generated with common inhalers remains in comparison poorly characterized. Here, we employ a so-called one-path airway model integrated into an airway-on-chip to explore the contribution of electrostatic forces to aerosol deposition along the respiratory tract. By comparing neutralized and charged particles (diameters 0.2 and 2 µm), we show that electrostatic forces significantly alter deposition patterns, foremost shifting deposition from the deep acinar region to more proximal airways in the small bronchial regions (i.e. bronchioles), in analogy to a screening phenomenon. Our experiments, complemented by nondimensional analysis, underscore conditions where electrostatics begin to dominate over traditional deposition mechanisms, thereby underlining the importance of recognizing the role of electrostatics towards pulmonary deposition.

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• Biological fluid dynamics
• Physiological flows