Introducing the Nose-Inspired PRO Filter
Air quality inside buildings matters as much as outdoor pollution, yet many conventional filters struggle to trap the tiniest particles in fast-moving air. A team led by Associate Professor Sanghyuk Wooh at Chung-Ang University has developed a breakthrough: particle-removing oil-coated (PRO) filters that mimic the way nasal hairs trap particles with mucus. The result is a reusable, high-performing filter that can handle a range of pollutants without sacrificing airflow.
Why Traditional Filters Fall Short
Most standard filters rely on trapping particles through the material’s physical structure and van der Waals forces, which are relatively weak. While fine for larger debris, these forces can fail when dealing with ultrafine dust, pollen, or smoke. Particles captured on a filter can be dislodged by shifts in airflow or strong ventilation, turning clean air back into contaminated air. This not only reduces efficiency but also increases energy use as systems work harder to compensate.
Limitations of Sieve-Like Filtration
As filters become finer, airflow is hindered, raising energy costs and shortening filter life. The problem compounds when tiny particles bypass the sieve or are displaced by turbulent air. The PRO filter addresses these issues by changing the interaction between particles and the filter surface rather than just trying to trap them through size alone.
The Oil Coating: A Natural Solution
Inspired by mucus-coated nasal hairs, Wooh’s team coats filter fibers with a very thin, stable layer of oil. The coating is engineered so that the oil spreads evenly across polymer brushes on the filter material, creating a sticky, yet permeable, surface. Unlike previous liquid coatings, this oil layer does not clog pores, ensuring continued airflow and low energy penalties.
Capillary Forces Take Center Stage
When particles encounter the oil-coated surface, capillary forces generate surface tension that pulls and holds them tightly onto the fibers. These forces are measured in the micronewton to sub-micronewton range—thousands of times stronger than van der Waals attractions—greatly reducing the risk of redispersion under changing airflow.
<h2 Real-World Performance and Benefits
Lab testing showed PRO filters outperforming conventional filters across a spectrum of particle sizes, from pollen to ultrafine dust. Filtration efficiency increased by 10–30% without compromising airflow, potentially lowering HVAC energy consumption. More importantly, the oil coating maintains effectiveness even when airflow direction changes, making PRO filters well-suited for dynamic environments such as subways, industrial zones, and outdoor gathering spaces.
Reusability and Cost-Effectiveness
Another standout feature is reusability. When the oil becomes dirty, it can be washed away and replaced with a fresh layer, extending filter life and reducing plastic waste compared to disposable options. Field tests in real HVAC systems demonstrated the PRO filter lasting roughly twice as long as standard filters with similar or better dust capture, while cutting energy use by about 20%.
<h2 A Path Toward Smarter, Sustainable Filtration
The PRO filter represents a shift from brute-force trapping to smarter, chemistry-driven design. By leveraging a tailored oil-polymer pairing and a remarkably thin coating, the filters maintain airflow, resist redispersion, and deliver longer service life. The potential applications span schools, hospitals, factories, and public transit hubs, with opportunities to add automatic oil refresh mechanisms or adaptive responses to changing air conditions.
As Wooh notes in the Nature publication, this approach is the first to suppress dust redispersion while enabling multidirectional filtration without extra energy input. If adopted widely, PRO filters could redefine how buildings—and their occupants—experience clean air, with meaningful environmental and cost benefits.
