Significance of the Science

Per- and polyfluoroalkyl substances (PFAS) - known as "forever chemicals" - are persistent, toxic contaminants that threaten drinking water and human health, yet current detection methods are costly and complex. This work presents an ultrasensitive remote gate field-effect transistor (FET) sensor that detects perfluorooctane sulfonic acid (PFOS) in tap water at ~250 parts per quadrillion—far below the US EPA’s 4 ppt limit. The device offers rapid (<2 min), reversible response with strong selectivity against common ions and pollutants. Mechanistic studies highlight roles of adsorption and charge interactions, guiding the design of improved PFAS capture probes and enabling continuous, in-line monitoring for safer water systems. This study represents the most sophisticated PFOS sensor to date.

Highlights

• Reversible detection: The FET sensors achieve ppt-level sensitivity with reversible binding, addressing a key limitation of most ultra-trace chemical sensors that operate irreversibly.

• High sensitivity: Sensors reliably detected PFOS at levels well below the US EPA’s 4 ppt health advisory threshold for drinking water.

• Tap water compatibility: Device performance was validated in real-world tap water, overcoming challenges of ionic strength and interfering species.

• Scalable design: The sensor platform is based on scalable fabrication methods, positioning it for integration into point-of-use devices.

• Potential applications: Enables continuous, on-site monitoring of PFAS in drinking water systems, supporting environmental surveillance and public health.

Summary

In this study, we developed a reversible, parts-per-trillion-sensitive field-effect transistor sensor for detecting PFOS in tap water. Unlike conventional single-use or irreversible detection schemes, the FET device demonstrates stable, reproducible measurements with the ability to reset between exposures. The approach achieves detection limits below the US EPA advisory level, showing robustness in complex water matrices. This innovation paves the way for deployable, real-time PFAS monitoring tools, bridging the gap between laboratory-based assays and field-ready environmental sensors.

Read more: https://www.nature.com/articles/s44221-025-00505-9