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New sensor can detect 'forever chemicals' in drinking water

A team of chemists from the Massachusetts Institute of Technology (MIT) has designed a breakthrough method for the detection of perfluoroalkyl and polyfluoroalkyl substances (PFAS). The experts constructed a sensor capable of identifying these hazardous chemicals in water at remarkably low concentrations. 

Since PFAS – widely used in consumer products such as food packaging, nonstick cookware, and water-repellent clothing – are notorious for their persistence in the environment, they are widely known as “forever chemicals.” 

Health risks of forever chemicals m water

The health implications of PFAS exposure are severe, with studies linking them to a range of adverse effects including cancer, reproductive issues, and disruptions to the immune and endocrine systems.

The innovative sensor developed by the MIT team is designed to detect PFAS levels down to 200 parts per trillion in water samples, representing a significant advancement in our ability to monitor these compounds. 

Detecting harmful PFAS

This device not only has the potential to empower consumers to test their own drinking water but also holds promise for industries that utilize PFAS in their manufacturing processes, such as semiconductor production and firefighting equipment fabrication.

“There’s a real need for these sensing technologies. We’re stuck with these chemicals for a long time, so we need to be able to detect them and get rid of them,” said senior author Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT. 

The research team, including former MIT postdoc Sohyun Park and graduate student Collette Gordon, has demonstrated a profound understanding of the urgency and necessity of such innovations in the face of enduring PFAS contamination.

PFAS chemical contamination in drinking water nationwide

PFAS chemicals, given their extensive application across a myriad of consumer goods, from stain-resistant fabrics to cosmetics and firefighting foams, have been a staple of industrial use since the 1950s. 

However, their environmental and health impacts have only come to light in recent decades, revealing contamination in drinking water sources nationwide. In response, the Environmental Protection Agency (EPA) established “advisory health limits” for two of the most hazardous PFAS compounds in 2023, aiming to set a benchmark for safe water consumption levels.

Traditionally, assessing PFAS contamination in water has been a laborious and expensive process, requiring specialized laboratory equipment and weeks of waiting for results. Addressing this challenge, the MIT sensor utilizes lateral flow technology, akin to that of rapid Covid-19 tests, offering a faster, more cost-effective solution. 

How the sensor works

The novel sensor embeds polyaniline, a polymer that transitions between semiconducting and conducting states, onto a nitrocellulose paper strip.

When exposed to PFAS, the sensor harnesses a surfactant to extract the compounds from the water, leading to a measurable change in the polymer’s electrical resistance, which can be quantified and relayed to an external device such as a smartphone.

The sensor specifically targets acidic PFAS compounds, including PFOA and perfluorobutanoic acid (PFBA), marking a significant step toward comprehensive PFAS detection. While the current sensitivity levels of the sensor do not yet meet the stringent EPA guidelines, the research team is optimistic. 

Revolutionary detection system

By scaling up the technology to process larger water volumes through a polyaniline membrane, they anticipate achieving the sensitivity required to detect even lower concentrations of PFAS, aligning with EPA advisories.

“We do envision a user-friendly, household system,” Swager explained. “You can imagine putting in a liter of water, letting it go through the membrane, and you have a device that measures the change in resistance of the membrane.” 

Such a system would not only revolutionize PFAS detection for consumers, enabling them to take immediate action if contaminants are present, but also assist manufacturers in ensuring the environmental safety of their wastewater.

This breakthrough in PFAS detection technology signifies a critical advancement in our ongoing battle against forever chemicals. By providing a practical, efficient means of monitoring these pervasive contaminants, the team’s work offers hope for mitigating the extensive health and environmental risks posed by PFAS. 

As the technology continues to develop, it promises to play a crucial role in our collective efforts to understand, manage, and ultimately reduce PFAS contamination in our environment.

The study is published in the journal Proceedings of the National Academy of Sciences.


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