On the design of particle filters inspired by animal noses

Abstract

Passive filtering is a common strategy to reduce airborne disease transmission and particulate contaminants across scales spanning orders of magnitude. The engineering of high-performance filters with relatively low flow resistance but high virus- or particle-blocking efficiency is a non-trivial problem of paramount relevance, as evidenced in the variety of industrial filtration systems and face masks. Next-generation industrial filters and masks should retain sufficiently small droplets and aerosols while having low resistance. We introduce a novel 3D-printable particle filter inspired by animals’ complex nasal anatomy. Unlike standard random-media-based filters, the proposed concept relies on equally spaced channels with tortuous airflow paths. These two strategies induce distinct effects: a reduced resistance and a high likelihood of particle trapping by altering their trajectories with tortuous paths and induced local flow instability. The structures are tested for pressure drop and particle filtering efficiency over different airflow rates. We have also cross-validated the observed efficiency through numerical simulations. We found that the designed filters exhibit a lower pressure drop, compared to commercial masks and filters, while capturing particles bigger than approximately 10 μm. Our findings could facilitate a novel and scalable filter concept inspired by animal noses.

A new aerodynamic endonasal filtration technology for protection against pollutants and respiratory infectious agents: evaluation of the particle filtration efficacy

“…Recently, a novel bioinspired 3D-printed filter design with five levels of tortuous airflow channels was shown to have a low pressure drop compared to commercial masks with higher capturing efficiency of particles less than Filtration efficiencies of endonasal device tested at low (30%-38%) relative humidity under accelerated saturation, per size of challenge particles and per size of device under testing. 12 μm with >80%, however, it also exhibited lower capturing efficiency with smaller particle diameters and higher velocity of airflow (20).…”

Meta-Aerogel Electric Trap Enables Instant and Continuable Pathogen Killing in Face Masks

“…This ultrafast sterilization was achieved through the structural design of aerogels; that is, large numbers of dielectrophoretic–aerodynamic traps were constructed to manipulate, capture, and inactivate bacteria (Figure b). , The nonuniform electric fields, generated around the tips of CNTs in the cell walls (Figure f), resulted in dielectrophoresis that can directionally transport to the electrode surface for particle capture . On the other hand, inspired by the long and curved turbinates in the nasal cavity of animals which helps the capture of particles to achieve a better sense, an interconnected and tortuous hierarchical cellular architecture of METs along the air direction was constructed for highly efficient filtering. , In this regard, the serpentine pathways and induced local flow instability divert the trajectories of particles, allowing for aerodynamic entrapment and effective particle retention. Furthermore, the cell walls with a nano/microstructure of self-knotted networks can effectively intercept the collided pathogens in the airflow .…”

“…27 On the other hand, inspired by the long and curved turbinates in the nasal cavity of animals which helps the capture of particles to achieve a better sense, an interconnected and tortuous hierarchical cellular architecture of METs along the air direction was constructed for highly efficient filtering. 28,29 In this regard, the serpentine pathways and induced local flow instability divert the trajectories of particles, allowing for aerodynamic entrapment and effective particle retention. Furthermore, the cell walls with a nano/microstructure of selfknotted networks can effectively intercept the collided pathogens in the airflow.…”

Simplified models of aerosol collision and deposition for disease transmission

“…As a result of the curvature of the nasal cavity, particles and aerosols are more likely to collect during inhalation, allowing us to smell. In particular, the highly tortuous air passage in animal noses can influence particle deposition [22] [23]. Numerical simulations have shown that the movement and deposition of particles in the nasal cavity are significantly affected by changing flow and particle size.…”