New sensor offers cheap and fast way to detect harmful “forever chemicals” in drinking water
Researchers have developed a groundbreaking sensor capable of detecting minute quantities of perfluoroalkyl and polyfluoroalkyl substances (PFAS). (CREDIT: Creative Commons)
MIT scientists have developed a groundbreaking sensor capable of detecting minute quantities of perfluoroalkyl and polyfluoroalkyl substances (PFAS), pervasive chemicals present in various consumer products.
These substances, referred to as "forever chemicals" due to their resistance to natural degradation, have been associated with numerous adverse health effects, including cancer and reproductive issues.
The newly designed sensor can detect PFAS levels as low as 200 parts per trillion in water samples. This innovation not only provides a means for consumers to assess the safety of their drinking water but also holds potential applications in industries heavily reliant on PFAS, such as semiconductor manufacturing and firefighting equipment production.
A PFAS sensing platform based on polyaniline (PANI) polymer and e-361 LFA. (CREDIT: PNAS)
Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT and senior author of the study published in the Proceedings of the National Academy of Sciences, emphasizes the critical need for sensing technologies to address the persistent presence of these chemicals.
Swager states, "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."
PFAS, commonly found in food packaging, nonstick cookware, and various consumer goods, pose significant environmental and health concerns. These chemicals, utilized since the 1950s, can contaminate water, air, and soil through industrial processes and waste disposal practices.
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Their widespread presence in drinking water sources across the United States has prompted regulatory action, with the Environmental Protection Agency (EPA) establishing advisory limits for particularly hazardous PFAS compounds, including perfluorooctanoic acid (PFOA) and perfluorooctyl sulfonate (PFOS).
To address the challenges posed by PFAS contamination, the MIT team engineered a sensor utilizing lateral flow technology, akin to rapid Covid-19 and pregnancy tests.
Unlike traditional laboratory-based mass spectrometry testing, this sensor offers a faster and more cost-effective solution for detecting PFAS. By leveraging a unique polymer called polyaniline, which exhibits conductivity changes in the presence of protons, the sensor can accurately quantify PFAS levels in water samples.
This technology, currently capable of detecting concentrations as low as 200 parts per trillion for certain PFAS compounds, is undergoing refinement to meet stringent EPA advisory levels.
The sensor's operational principle involves depositing polyaniline-coated polymers onto nitrocellulose paper strips, supplemented with a surfactant capable of extracting PFAS from water samples.
Resistance and conductivity measurement of the F-PANI test line in the 374 e-LFA using four-point probe system. (CREDIT: PNAS)
When PFAS molecules interact with the sensor, protons are transferred to the polyaniline, inducing a shift in its electrical resistance. This alteration in resistance, measurable via electrodes and compatible with external devices like smartphones, enables precise PFAS quantification.
Although the current sensor iteration falls slightly short of meeting EPA guidelines, ongoing research aims to enhance sensitivity through the development of a larger-scale device.
This upgraded device would employ a polyaniline membrane capable of processing larger volumes of water, potentially increasing sensitivity by over a hundredfold. Swager envisions a user-friendly household system, where individuals can assess water safety by simply passing it through the membrane and monitoring resistance changes.
In addition to safeguarding drinking water quality, the sensor holds promise for industrial applications, allowing manufacturers to assess the safety of water used in production processes. Detected PFAS contamination can prompt the utilization of commercially available filters to mitigate risks associated with exposure.
The MIT sensor represents a significant step forward in addressing the pervasive threat of PFAS contamination. By offering a rapid, cost-effective detection solution, this innovation underscores the importance of proactive measures in safeguarding public health and environmental integrity against the harmful impacts of forever chemicals.
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