Abstract: A graphene transistor system for measuring electrophysiological signals uses flexible epicortical and intracortical arrays of graphene solution-gated field-effect transistors (gSGFETs) to record infraslow signals alongside signals in the typical local field potential bandwidth. The graphene transistor system includes a processing unit, and at least one graphene transistor (gSGFET) a tunable voltage source connected to the drain and source terminals of the transistor (gSGFET), and at least one filter configured to acquire and split the signal from the transistor into at least a low frequency band signal and high frequency band signal, which are amplifiable with a gain value.