Tuning of Gate Electrostatics to Amplify Mercury Sensing Performance of Functionalized Field Effect Transistor

According to the World Health Organization (WHO), mercury is one of the top ten toxic groups of substances that can pose the greatest threat to human life. Very minor contamination with mercury can adversely impact the nervous, digestive, and immune systems of the lungs, kidneys, skin, and eyes, resulting in severe health problems, including death. Conventional detection techniques are incredibly complex, costly, and lack portability. This article describes a highly sensitive, selective, and stable field effect transistor (FET)-based sensor for efficiently detecting mercury ions in water. Glutathione-reduced graphene oxide (glu-rGO) is chosen as the sensing material. The operating gate voltage of the device is optimized to -4.98 V to achieve maximum response. At a gate voltage of -4.98 V, the device’s sensitivity is evaluated as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.04~\mu $ </tex-math></inline-formula> A/ppb for 1.2 ppb mercury compared to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.51~\mu $ </tex-math></inline-formula> A/ppb at zero gate voltage. The device is tested against six common heavy metal ions and is found to be highly selective toward mercury. Therefore, the glu-rGO-based FET device is promising for future portable, economical, and user-friendly mercury ion detector systems.