A high school student in the United States, Mia Heller, has developed a low-cost water filtration prototype that can remove up to 96% of microplastics using a magnetic liquid known as ferrofluid. The project, presented at the Regeneron International Science and Engineering Fair 2025, offers a simple and potentially affordable approach to a growing global problem. The idea was inspired by water contamination concerns in her local area in Virginia, where residents were dealing with microplastics and PFAS pollution without government-funded solutions. Microplastics, now found in oceans, drinking water and even human tissue, are difficult to filter out using conventional methods. While still at a prototype stage, the system has drawn attention for combining relatively high efficiency with a design that could be adapted for wider use.
How the filter removes microplastics
Unlike traditional filtration systems that rely on physical barriers, this method uses magnetic separation. The process involves introducing ferrofluid, a magnetic oil, into contaminated water, where it binds to microplastic particles. A magnetic field is then applied to pull both the ferrofluid and attached plastics out of the water. The current prototype consists of a three-module system roughly the size of a standard bag of flour, designed to process about one litre of water at a time. The system operates in a closed loop, allowing partial recovery and reuse of the ferrofluid, reducing waste and maintenance needs.
What the results show
The prototype has demonstrated a microplastic removal efficiency of approximately 95.5%, along with a ferrofluid recovery rate of around 87%. These results were measured using a custom-built turbidity sensor developed by the student to track particle levels and filtration accuracy. The performance places the system within, and in some cases above, the range of many conventional filtration methods, which typically achieve removal rates between 70% and 90% under standard conditions. While these findings are based on controlled testing, they indicate that the approach is technically viable at a smaller scale.
Why microplastics are a growing concern
Microplastics are tiny particles ranging from about 1 nanometre to 5 millimetres in size, according to environmental definitions. They originate either as primary microplastics, manufactured for products like cosmetics, or as secondary microplastics formed from the breakdown of larger plastic waste. These particles have been detected across ecosystems and within more than 1,300 species, including humans. Studies have found them in organs such as the brain, blood, lungs and even the placenta. While the full health impact is still being researched, scientists have linked microplastic exposure to potential risks including cardiovascular, respiratory and neurological conditions, though the evidence remains inconclusive.
MicroplasticsMicroplastics
What experts and researchers are saying
The project has been noted for demonstrating how relatively simple materials can be used to address a complex environmental issue. The student developed the system after observing the high maintenance and cost of traditional membrane-based filters used at home, aiming to create a solution that reduces both expense and upkeep. The result is a filtration method that avoids solid membranes altogether.Experts have described the idea as promising. Toxicologist Matthew Campen called it ‘a really great idea’ and noted that it represents the kind of innovation needed to tackle microplastic pollution. At the same time, he and others emphasised that further validation is required to confirm that the system removes microplastics completely without leaving behind other residues.Researchers studying microplastics have also highlighted the urgency of the issue. ‘We still have a lot to learn about how microplastics affect our health,’ said Dr Megan Hill, assistant professor of chemistry at Colorado State University. Megan Jamison, a doctoral candidate at Ohio State University, noted that ‘for humans, drinking water is a concern because some of the smaller microplastics are making it through treatment and people are ingesting them at unknown rates with unknown effects’.Adding a broader public health perspective, Dr Desiree LaBeaud, a professor of paediatrics at Stanford Medicine, said, ‘All of us need to stop using plastic as much as we can to protect our health, especially single-use plastics’. Together, these views underline both the promise of new filtration approaches and the need for careful testing and real-world validation.
Questions around safety and scalability
Despite its potential, the system raises several practical considerations. One key concern is whether any ferrofluid particles remain in the water after treatment, as this could introduce new contaminants. Experts stress that captured microplastics must also be disposed of safely to avoid re-entering the environment.Scalability remains another challenge. While the current prototype is designed for small-scale use, such as household filtration, expanding it to municipal water systems would require further engineering and cost analysis. The student herself has suggested that the system may be most suitable for under-the-sink or home-based use, particularly given the current cost of producing ferrofluid at scale.
Why the project stands out
The innovation is notable not only for its technical approach but also for its origin. Developed by an 18-year-old high school student, the project reflects a practical attempt to solve a real-world problem using accessible materials. It introduces a non-traditional filtration method while maintaining a focus on affordability, reuse and reduced maintenance. The system also earned recognition at a major global science competition, where it received an award for its design and potential impact.Further development of the system would require professional validation of results, improvements in ferrofluid recovery, and testing under real-world conditions. The student has expressed interest in eventually bringing the technology to market, though for now the focus remains on refining the prototype and confirming its effectiveness through further research.
