On the design of particle filters inspired by animal noses

TL;DR

This paper presents a novel 3D-printed particle filter inspired by animal nasal structures, achieving high efficiency and low resistance by using tortuous airflow channels, with potential applications in masks and air filtration systems.

Contribution

The paper introduces a bio-inspired, 3D-printed filter design with spaced channels and tortuous paths, improving airflow and particle trapping over traditional filters.

Findings

Lower pressure drop than commercial masks and filters.

Effective particle trapping demonstrated through experiments and simulations.

Potential for scalable, flexible high-efficiency air filters.

Abstract

Passive filtering is a common strategy used to reduce airborne disease transmission and particulate contaminants in buildings and individual covers. The engineering of high-performance filters with relatively low flow resistance but high virus- or particle-blocking efficiency is a nontrivial problem of paramount relevance, as evidenced in the variety of industrial filtration systems and the worldwide use of face masks. In this case, standard N95-level covers have high virus-blocking efficiency, but they can cause breathing discomfort. 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 a wide range of airflow rates. We have also cross-validated the observed efficiency through numerical simulations. The designed filters exhibit a lower pressure drop than the commercial mask and air filters (N95, surgical, and high-efficiency particulate air (HEPA)). The concept provides a new approach to developing scalable, flexible, high-efficiency air filters for various engineering applications.