Amine and Thiol Cofunctionalized Reduced Graphene Oxide Field-Effect Transistor for the Selective Detection of Formaldehyde

This work presents a field-effect transistor-based sensor for the detection of formaldehyde. Amine and thiol cofunctionalized reduced graphene oxide sheets are used as the sensing channel here. The functionalization is carried out by reducing graphene oxide with reduced l-glutathione, a naturally extracted intercellular antioxidant. The sensor is found to be highly selective toward detecting formaldehyde with strong immunity toward humidity. Furthermore, a density functional theory-based study is carried out, which reveals the functionalization process, indicating the orientation of the molecule and attached functional groups on the graphene surface. It shows that the thiol group of the glutathione attaches to the graphene sheet while the exposed amine groups are responsible for detecting formaldehyde. A reversible Schiff's base reaction mechanism between formaldehyde and the free amine ends in the glutathione molecule is proposed to be responsible for the sensing mechanism. A selective sensing layer, along with a compatible sensor platform, can be developed based on the presented principles for the early detection of lung cancer from human breath.