Tunable Sensitivity in Graphene-Based Soil Moisture Sensors via Controlled Vapor Phase Reduction Method

In this letter, a resistive-reduced graphene oxide (RGO)-based sensor is developed using chemical vapor reduction. This resistive sensor has a good sensitivity to soil moisture. The RGO is synthesized by the vapor phase reduction of graphene oxide (GO) using hydrazine hydrated as a reducing agent at room temperature. The controlled reduction of GO is achieved by varying the exposure time of it to the hydrazine hydrate vapor. The sensing results indicate the p-type sensing nature of the fabricated RGO sensor. The RGO sensor shows ∼5.68% and 121% sensor response for 2% and 15% soil moisture content, respectively. The decrement of sensor response is observed with the increment of reduction time. This signifies the tunable sensitivity of our fabricated sensor via controlled vapor phase reduction by varying its reduction parameter. The scope for developing RGO-based soil moisture sensors in the agricultural sector has been less explored till now.