Design of new-generation scalable filters with tortuous pathways inspired from animal noses *

We have explored new-generation filter pathways, taking inspiration from the topologically complex nasal cavities found in high-olfactory animals (e.g., dogs, pigs). Inhaled particulates are more efficiently screened as the air recirculates through the tortuous nasal passages in these animals, thereby augmenting their olfaction. The proposed bio-inspired filters would use regular airflow paths with continuous tortuosity, inducing a reduced resistance inside conduits and a high likelihood of particle-trapping by altering their trajectories with tortuous paths and local flow instability. We have tested the iterative designs for pressure drop and particle filtering efficiency over a wide range of airflow rates (3–73 L/min) using manometers and optical technique, a subset of which corresponds to the range for steady to forceful breathing (15–55 L/min). We have also cross-validated the observed screening efficiency through theory and LES-based numerical simulations. The proposed filters exhibit a lower pressure drop than commercial mask filters (e.g., N95, surgical) by a factor of 2 under similar filtering thresholds.