Real-time detection of mercury ions in water using a reduced graphene oxide/DNA field-effect transistor with assistance of a passivation layer

Ultra-sensitive and label-free reduced graphene oxide (rGO)-based field-effect transistor (FET) sensors have been developed. Al₂O₃ on the rGO as a passivating layer can avoid free ions' contribution to the sensing signals and can prevent the degradation of the intrinsic electrical properties of rGO during the immobilization of probes on rGO. The rGO FET sensor, using a single-stranded Hg²⁺-dependent DNA probe, shows high sensitivity and selectivity for real-time detection of Hg²⁺ in an underwater environment. Our work shows that optimization of an rGO FET structure can provide significant performance enhancement and profound fundamental understanding for the sensor mechanism.