Trace Level Arsenic(III) Ion Detection in Water with Liquid-Gated rGO/GO Field Effect Transistor Based Sensor

Abstract

Inorganic arsenic ions in consumable water poses a major threat to human health and well-being. Thus, continuous monitoring of As(III) ions is essential. Most of the graphene transistor uses SiO2 or HfO2 as the common dielectrics and graphene or reduced graphene oxide (rGO) acts as the receptor layers deposited on the channel or as semiconductor. The present study illustrates the fabrication of a liquid gated rGO field effect transistor (FET) by using semiconducting rGO and graphene oxide (GO) dielectric that can selectively detect trace levels of As(III) ions in consumable water. The as fabricated device showed excellent As(III) ion sensing performance with a maximum response of 500% for 40 ppm of As(III) with fast response and recovery times of 17.4 s and 11.76 s respectively. The limit of detection (LOD) and limit of quantification (LOQ) of the device was found to be 0.720 ppb and 2.40 ppb respectively at room temperature when operated at an optimized Vgs = 0.5 V. The sensor demonstrated excellent specificity towards As(III) ions when exposed to similar concentrations of other comparable ions. It was found to be repeatable till 70 days with an accuracy of 98.4% and a response deviation of 2.2%. To further improve the quantification efficiency in mixed environment, the cross-sensitivity with Ni(II) ions was addressed by using linear regression algorithm which showed a R2 Score of 0.9732. An adsorption based model was put forward to demonstrate the sensing and the device functioning of the sensor. The sensor coupled to the as-developed optimized algorithm performed exceptionally under real-time environment when tested for tap and drinking water samples thereby showing an accuracy of 98%. Thus, the rGO FET based sensor outperforms conventional rGO based sensors and hence can be used as their suitable alternative to achieve enhanced As(III) ions sensing in solution.