(79e) Two-Dimensional Molybdenum Disulfide Based Field Effect Transistor Sensor for Pfas Detection in Water

Per- and poly-fluoroalkyl substances (PFAS), a large group of persistent anthropogenic organic chemicals widely applied in industrial chemical processes and consumer products, have become an emerging concern because of their adverse environmental effects and human health. Traditional technologies such as liquid chromatography-mass spectroscopy and gas chromatography-mass spectroscopy are often not appropriate for continuous monitoring of the environment due to the high expenses and requirement of well-equipped laboratories with highly trained personnel. Therefore, developing a simple, inexpensive, and scalable method for rapid and in-situ detection of PFAS molecules in the environment, especially in drinking water, is of primary importance.

Here, we report a novel field effect transistor (FET) based on two-dimensional (2D) molybdenum disulfide (MoS₂) for PFAS detection in water. High-density MoS₂ flakes were synthesized by chemical vapor deposition and transferred on the channel areas between source-drain electrodes. Then, a hexagonal boron nitride (h-BN) film was transferred to the MoS₂ layer as an encapsulation layer to improve stability by preventing chemical degradation upon exposure to air or water. A pyrene-based linker molecule was used to bond PFAS molecules to the FET channel area, assisted by the hBN films. The PFAS FET sensor can be fabricated by functionalizing the channel area with PFAS specified molecular imprinting polymer (MIP) probe molecules for selective detection. It was observed that adding a pyrene-based linker produces an n-type doping effect by increasing the electron concentration in the channel, which increases the electrical conductivity. Finally, the performance of the device was characterized by measuring the changes in electrical conductivity of the MoS₂ channel with different concentrations of PFAS molecules. Our results demonstrate that the FET sensor exhibits a linear response to PFAS in the ppb to ppt concentration range, with a high sensitivity of <0.01 ppb and good selectivity. This work provides an essential advancement in developing next-generation electronic sensors, which can be a cost-effective, rapid, and sensitive detection tool for in-situ PFAS monitoring in water.