Introduction: A Natural Idea Behind a High-Tech Filter
Air quality inside buildings isn’t just about what you can see. Tiny particles—dust, pollen, smoke—float in the air and can harm health when inhaled. Traditional filters struggle to capture these particles effectively, especially under changing airflow, leading to re-entrainment and wasted energy. Now, researchers are turning to nature for a better solution: a reusable air filter that mimics the nose’s particle-trapping mechanism.
The PRO Filter Breakthrough
Led by Associate Professor Sanghyuk Wooh at Chung-Ang University, the team introduced particle-removing oil-coated (PRO) filters that coat the filter fibers with a very thin, stable layer of oil. This biomimicry mirrors how mucus-coated nasal hairs trap particles, but applies it to synthetic filter materials. The oil is sprayed onto polymer-coated fibers in a way that ensures even spread and strong adhesion, creating a surface that attracts and holds particles with capillary forces far stronger than van der Waals attractions used in traditional filters.
Why This Matters
Conventional filters rely on sieving and weak molecular attractions. While fine particles can be captured, they are often dislodged by airflow or direction changes, allowing dirty air to sneak back into the stream. The PRO approach adds a thin liquid layer that does not clog pores, so airflow remains smooth and energy-efficient, while particles become trapped by surface tension and capillary effects around the oil-coated fibers.
How It Works
The oil’s chemistry is matched to the polymer brushes on the fibers, ensuring even coating and durable adhesion. The resulting capillary forces act like tiny grips, pulling particles toward the fibers and holding them in place. In tested conditions, these forces are thousands of times stronger than van der Waals forces, significantly reducing the chance of re-entrainment even in multidir ection airflow or gusts.
Laboratory and Real-World Performance
In lab scenarios across a range of particle sizes—from pollen to ultrafine dust—the PRO filter outperformed standard filters by 10–30% in filtration efficiency without adding resistance to airflow. The energy footprint of HVAC systems dropped accordingly, thanks to easier airflow and longer-lasting performance.
More importantly, the PRO filter demonstrated resilience under dynamic conditions. Filtration maintained its edge as airflow intensified or shifted, keeping captured particles in place instead of releasing them. This capability makes PRO filters especially suitable for environments with variable airflow, such as subways, industrial zones, and outdoor spaces near smoke plumes.
Reusability and Sustainability
A standout advantage is reusability. When the oil becomes dirty or saturated, it can be washed off and a fresh oil layer reapplied, restoring performance. Field trials with real HVAC systems showed the PRO filter lasting about twice as long as conventional filters and reducing energy use by roughly 20%. This translates into lower maintenance, fewer replacements, and less plastic waste from disposable filters.
A Vision for Cleaner, Smarter Filtration
The PRO filter represents a shift in air purification philosophy: excellent performance does not require more complex machinery. Instead, it leverages chemistry and design to harness natural mechanisms. The approach invites customization—oil coatings could be tailored for specific settings, from schools and hospitals to factories—potentially with auto-refresh features that adapt to changing air conditions.
As the research moves toward commercialization, the implications are clear: smarter, more energy-efficient filtration that aligns with sustainable building practices. The study, published in Nature, signals a future where clean air in public and commercial spaces could be achieved with simple, reusable solutions rather than bulky, energy-intensive systems.
