This work provides an experimental characterization and equivalent circuit modelling of electrochemically gated field effect transistors (EGFETs) using a graphene layer. The aim is to demonstrate the detection limit of these sensing devices for bioelectronics applications. Towards that, we present a detail study of the; (i) sources of intrinsic noise, (ii) the effect of ionic density in charge transfer resistance and (iii) the existence of parasitic conducting paths in the surrounding electrolyte.

To investigate the liquid-based applications of graphene based EGFETs, quantifying the basic physical properties of graphene/solution interface is crucial. Towards that, we present a detail study of zero bias charge transfer resistance by using different type of ionic solutions and cell culture mediums. Measurements of the electrical noise were also performed to determine the EGFET detection limit.

The performance of the EGFET to record the electrophysiological signals was evaluated using adult zebra fish heart and electrogenic cell cultures. The electrocardiogram of the zebrafish heart was monitored with signal-to-noise-ratio higher than 7.

This contribution also discusses the application of graphene based EGFETS to measure electrophysiological signals in cell cultures. For instance, ultra-week extracellular signals resulting from cell metabolic activity or low frequency calcium waves.

Keywords. Graphene, electrochemically gated field effect transistor, charge transport, intrinsic noise, extracellular signals.