It is found in the environment, in food, and in the bodies of both animals and humans: microplastics are everywhere. In 2025, researchers detected these particles in human livers, kidneys, and, for the first time, in brains. An analysis of tissue samples from 2016 and 2024 revealed an increase in the measured concentration of micro- and nanoplastics (MNP). These are plastic particles with diameters ranging from 500 micrometres down to 1 nanometre. While samples from 2016 contained a median of 3.34 micrograms of MNP per gram, the figure in 2024 stood at 4.91 micrograms.
This 47 percent increase within eight years suggests that as environmental pollution grows, so too does our uptake of microplastics.
The health consequences remain insufficiently researched, even though studies point towards toxic, inflammatory, and hormone- or DNA-altering effects. International experts recently called for a standardised, forensically inspired approach to research regarding microplastics in human tissue. The goal is to better understand exactly how far these particles penetrate the body and what impact they have on us.
Once these tiny plastic particles enter the environment, their absorption into the human body is almost impossible to avoid, as we breathe them in and consume them through our food.
To keep the load as low as possible, microplastics should ideally not be released in the first place. With this in mind, a team of researchers from the University of Bonn, in cooperation with Fraunhofer UMSICHT, has developed a washing machine filter inspired by nature itself: fish gills served as the blueprint. Instead of plankton, the developed system filters microplastics—and does so highly efficiently. Up to 99.6 percent of microplastics were successfully removed from the wastewater.
How microplastics enter the environment
The washing machine is one of the most significant entry points for microplastics into the environment. Alongside paint, tyre wear and plastic pellets, textiles are among the largest sources of microplastics within the European Union (EU). Every second, approximately four tonnes of textile fibres are produced, with polyester accounting for 59 percent of that total. Throughout their entire life cycle—from manufacture and wear to washing, drying, and disposal—textiles shed fine microfibres. In a four-person household, a washing machine can generate up to 500 grams of microplastics annually. Globally, washing our clothes releases around half a million tonnes of microplastics into the oceans every year. This is equivalent to roughly three billion polyester T-shirts.
To date, washing machines are not fitted with microplastic filters as standard. Consequently, the fibres enter wastewater and sewage treatment plants unimpeded. In the form of sewage sludge, which is spread on fields as fertiliser, microplastics ultimately end up in the environment. This is a cycle that must be broken.
“I realised that there is a great need to reduce microplastics in the environment. However, there are very few effective solutions,” Dr Leandra Hamann, from the research team at the University of Bonn’s Institute of Organismic Biology, told RESET. This led the scientist to search for new filtering mechanisms that overcome the weaknesses of existing systems. Many conventional filters either fail to retain microplastics adequately or become clogged very quickly.
Searching for inspiration in nature
Bionics—or biomimetics—is a field of research that draws on models from the natural world to develop innovative technical solutions. Leonardo da Vinci is considered a pioneer of this approach, having applied the mechanics of bird flight to flying machines. Centuries later, Dr Hamann also set out to find inspiration in nature. She studied sponges, crustaceans, molluscs, flamingos, manta rays, whales, and fish—with the aim of identifying suspension feeders. These are organisms capable of separating particles from the surrounding water.
Out of 35 identified filtering mechanisms, fish ultimately came out on top, as they filter particles of a similar size to microplastics. From the species studied, the research team selected ram-filtering fish as the blueprint for their filter technology. This group includes the Atlantic herring, sardines, and various species of mackerel.
The unique characteristics of ram-filterers
Ram-filterers take in water by swimming forward with their mouths open. Inside the fish, the water flows through a funnel-shaped system of gill arches equipped with densely arranged gill rakers. These structures function as a highly effective filter, separating almost all available plankton from the water.
“The species we studied possess a conical gill-raker geometry with structures that form a very fine sieve,” Hamann explains. Instead of flowing head-on through the filter, the water flows laterally along the gill arches. This flow pattern offers a decisive advantage: particles do not deposit immediately but are instead guided along the surfaces. Larger particles, such as plankton, are specifically collected while the filtered water escapes through the gills. In this way, the fish avoid clogging their filter structures—a feature that is also essential for technical filters.
Tiny particles get caught in the gill arches. The cleaning mechanism
In addition to filtration, the cleaning of the filter is critical to its functionality. This prompted the researchers to analyse the cleaning mechanisms of fish in order to imitate them. In ram-filterers, the plankton retained during filtration is directed into the gullet thanks to the funnel shape, until the fish swallows, thereby emptying and cleaning the system. This natural talent for self-cleaning, combined with high filtration performance without clogging, makes fish the ideal model for a microplastic filter.
From fish to filter
But how do you translate the anatomy of a fish into a technical system? This process took the research team—which included Hamann, her doctoral supervisor Dr Alexander Blanke, materials scientist Christian Reuß, and biologist Dr Hendrik Herzog—a significant amount of time to calculate. In fact, it took approximately eight years from the initial idea to the final filter, which is currently being patented. One of the greatest challenges was the process of abstraction, coupled with the question of how far the complex branchial basket system of fish could be simplified without technical losses.
The team approached the answer to this question in stages. “We built various filters that resembled the fish to varying degrees to find out what worked and which structures we could not replicate technically,” Hamann explained to RESET. To maximise filtration efficiency, the researchers used experiments and computer simulations to vary the filter size, the mesh width of the sieve structure and the angle of flow into the funnel. In total, four different filter elements were manufactured.
An efficient principle with broad potential
The end result was a highly efficient filter that removed up to 99.6 percent of microplastics from the wastewater. On top of this result, the filter was designed to be self-cleaning and to minimise clogging, just like its biological counterpart. The system features two separate discharge lines. The cleaned water flows out laterally through the filter mesh. Meanwhile, the particles are kept in motion along the conical filter surface and transported towards the outlet instead of becoming lodged in the filter.
Schematic model of the fish filter. At regular intervals, the system switches: the lateral outlet is briefly closed, while the second outlet at the end of the filter opens. This switching of the valves mimics the swallowing process of ram-filtering fish. Much like in the fish, the accumulated particles are specifically guided out of the filter system and collected. Through the combination of lateral flow, a conical shape, and periodic flushing, the particles remain in motion. The filter does not clog and repeatedly cleans itself.
The system was developed specifically for installation in washing machines to retain textile particles. However, its application is also conceivable in other pathways through which microplastics enter the environment. According to Hamann, the filter could be used anywhere that relatively large particles need to be filtered out of water and collected. For example, it could be used in road gullies. It is through these that tyre wear, one of the largest sources of microplastics, enters the wastewater, along with remnants of road markings, asphalt and vehicle parts.
Future technology waiting to be deployed
When we contacted Hamann, we reached her in Canada, where she is currently a guest researcher at the University of Alberta, studying the filtration mechanisms of sponges. Science still has much to learn from them, potentially applying these insights to environmental challenges. Following our exchange, one essential question remains: how likely is it that a microplastic filter will soon be fitted in every washing machine?
Surprisingly for the scale of the problem, there’s no shortage of solutions. As well as the filter system developed by Hamann and her team, numerous other approaches exist, from startups like the Slovenian company PlanetCare to various research organisations. One such example is FibrEX from Fraunhofer UMSICHT, which operates in a similar field. Although the FibrEX microplastic filter was patented, the initial interest from manufacturers and component builders waned. The primary reason is that immediate regulatory obligations to install microplastic filters in washing machines are not on the horizon. Consequently, the filter is currently being further developed for use in greywater treatment for residential buildings.
The FibrEX filter from Fraunhofer UMSICHT According to Hamann, there is fundamental interest in the fish-inspired filter from the commercial sector. However, what is currently missing is an industrial partner to test the technology under real-world conditions and bring it to market maturity. For both solutions, the challenge lies in the same critical step: the transition from the laboratory to the marketplace.
Policy frameworks for effective environmental protection
Although major manufacturers such as Siemens, Bosch, or Miele offer retrofit solutions, microplastic filters are not yet integrated into new washing machines as standard. As long as a mandatory regulatory framework is lacking, the responsibility remains solely with the consumer.
The European Union has set ambitious targets for 2030, aiming to reduce the release of microplastics into the environment by 30 per cent. Within the EU Textile Strategy, tackling the entry of microplastics from synthetic textiles is identified as a central area of action. However, exactly how these requirements will be implemented in practice remains open to question.
In France, a law has been in place since January 2025 requiring all new washing machines to be equipped with microplastic filters. Even though the specific details of the decree are still pending, this legal anchoring sends a vital signal to both manufacturers and consumers. Whether the EU follows suit is likely less a question of available technology and more one of political will to actively drive societal change. Among the many possible measures to reduce the flood of plastic in the environment, microplastic filters are certainly an approach that has an immediate effect and is globally scalable.
