Reduced graphene oxide-based needle-type field effect transistor for dopamine sensing

Owing to their intrinsic amplifying effect together with their temporal resolution, field-effect transistors (FETs) are gaining momentum for the detection of different biomolecules at ultralow concentration levels such as, for example, neurotransmitters, particularly if the concentration level of the analyte is below the detection limit of commonly used electrochemical sensing methods. We demonstrate the fabrication of a spearhead reduced graphene oxide (rGO)-based FET. The fabrication of the rGO-based FET by means of an electrochemical pulse deposition technique enables a controllable process including both the deposition and reduction of the deposited graphene oxide between two carbon nanoelectrodes to form the channel of the rGO-based FET. While using double-barrel carbon nanoelectrodes, the as-produced FETs offer new possibilities in terms of their applicability in very small volumes as well as the option of being positioned close to the desired measurement region. The fabrication process was evaluated and optimized to obtain rGO-based FETs with high performance. The as-fabricated devices were evaluated in terms of sensitivity and selectivity towards dopamine. The tested devices not only showed high sensitivity towards dopamine with a linear response ranging from 1 nM to 1\u3bcM, but also maintained a similar sensing performance in the presence of 500 \u3bcM ascorbic acid