Session: ASME Undergraduate Student Design Expo

Paper Number: 173951

Capacitive Sensor for Pfas Real-Time Detection in Water 

A 2015 study found that approximately 97% of Americans have PFAS(per/poly-fluoroalkyl substances) in their blood. They are linked to increased risk of infertility, accelerated puberty, and cancer. PFAS are most commonly consumed from groundwater-connected sources such as well water and tap water. However, PFAS are also common in bottled water. Once ingested, they linger in the body from days to decades. In particular, PFOA (perfluorooctanoic acid) has a half-life of 2-10 years in the human body. PFAS may also disrupt the body’s lipid regulatory systems and increase the risk of cardiovascular disease. Among its known effects, long-term studies on the health effects of PFAS are lacking. Trusted PFAS detection relies on relatively inaccessible laboratory instruments such as liquid chromatography tandem mass spectroscopy. Sending water samples to a laboratory can cost the consumer hundreds of dollars, and results are prepared after as long as ten days. Additionally, the diverse properties of PFAS make cost-effective, large-scale PFAS water treatment difficult to implement. Destroying PFAS often means pairing high temperatures with multiple other treatment processes. Efficient detection is necessary to judge the performance of such protocols. Individual consumers find use in testing for their own health awareness. Hence, high cost and long waiting times impede PFAS elimination progress and consumer peace of mind.
This study introduces a novel capacitive sensor that rapidly and quantitatively detects varying concentrations of PFOA in deionized (DI) water within the part per trillion (ppt) range. It is composed of a gold micro-electrode coated in an insulating layer, followed by an electroactive adsorbent composite. The insulating layer prevents short circuiting caused by the composite bridging the electrode terminals. The composite coating facilitates the capture of PFOA molecules and transfers charge to the electrode for capacitance measurement.
Through static-drop testing varying concentrations of PFOA-DI water solution, it was found that the sensor is capable of real-time quantitative detection within the ppt range. Higher concentrations are directly proportional to increases in signal. The sensor detects concentrations as low as 1ppt. By improving the selectivity of PFOA detection, a cheaper, accessible, and reliable PFAS testing solution would be available for implementation in household and industrial use. The compact sensing platform implies higher scalability. Future research involves further functionalizing the sensor for increased selectivity and sensitivity.  The ideal sensor can detect PFOA alone without interference from other substances in the water. Further sensitivity improvement into the part per quadrillion range would advance efforts to detect and ultimately eliminate PFOA from water.

Presenting Author: Chadley Gede New Jersey Institute of Technology

Presenting Author Biography: Chadley Chris Gede is an undergraduate researcher in the Advanced Energy Systems and Microdevices Laboratory at NJIT. Chadley is a junior undergraduate majoring in Mechanical Engineering. His work focuses on developing a sensor for the Real-Time detection of PFOS. He has an interest in mechanical engineering, clean water access, and electrochemistry.

Authors:

Chadley Gede New Jersey Institute of Technology
Eon Lee New Jersey Institute of Technology
Yudong Wang Georgia Instiitute of Technology