Fish gills inspire filter that catches 99% of microplastics from laundry

Every time you wash synthetic clothes, your machine releases thousands of tiny plastic fibers into the water system. A single polyester shirt can shed up to 1.5 million microplastic fragments in one cycle. A washing machine in a four-person household produces roughly 500 grams of these invisible pollutants annually—enough to add up to a serious problem across millions of homes worldwide.

Now researchers at the University of Bonn have designed a filter that could stop most of these fibers before they reach rivers and oceans. The innovation came from an unexpected place: the gills of anchovies and herrings.

How Fish Became the Blueprint

These filter-feeding fish have evolved an elegant system. As they swim forward with their mouths open, water flows in and plankton gets trapped by comb-like structures in their funnel-shaped gills. The food particles naturally roll toward the fish's throat while clean water passes out through the gill slits. No blockage. No maintenance required. Just physics and geometry working in concert.

The research team, led by scientist Hamann, replicated this design in synthetic form. They created a cone-shaped filter with a carefully calibrated mesh size and funnel angle. As microfiber-laden water flows through it, the fibers roll toward the back of the cone instead of lodging on the surface—the key difference that keeps the filter from clogging.

The system automatically collects the trapped fibers and removes them multiple times per minute. In testing, the filter captured more than 99% of microplastic fibers from washing machine wastewater, a record for this type of technology. The work was published in npg Emerging Contaminants and has already been filed for patent protection.

From Lab to Laundry Room

What makes this genuinely practical is what happens next. The researchers envision minor modifications to washing machines that would press the collected microplastics to remove excess water and compress them into a solid pellet. After a few dozen wash cycles, a household could simply remove this plastic block and dispose of it properly—turning an invisible problem into something tangible and manageable.

The filter addresses a real gap in current technology. Existing microplastic filters tend to clog quickly, requiring frequent replacement and maintenance. This design, borrowed from millions of years of fish evolution, avoids that problem entirely. It's a reminder that sometimes the most innovative solutions aren't invented from scratch—they're waiting in nature, refined by time.

If this technology moves from patent to production, it could transform how we handle synthetic clothing waste at the source, before it ever enters waterways.