Graphene Solution‐Gated Field‐Effect Transistor Array for Sensing Applications

Abstract

International audienc

Graphene Transistors for Bioelectronics

“…[18] Hall effect experiments employing solution-gated van-derPauw structures and Hall bars can be used to investigate the electrolytic gating of the carrier density in graphene. [36] Figure 6a shows the sheet conductivity as a function of the gate voltage obtained from these experiments revealing the expected Vshape curve typical of ambipolar transport, similar to the transistor curves shown in Fig. 4.…”

“…[36] As the potential level of the Ag/AgCl electrode is fixed with respect to the vacuum level, applying a voltage between this electrode and the graphene shifts the position of the Fermi level in the graphene, which controls the number of free carriers induced electrostatically. When the Fermi level reaches the Dirac point, i.e.…”

“…[43] Secondly, the double layer capacitance formed at the graphene/electrolyte interface shall be considered. [36] On the one hand, the charge in the graphene side of the interface is easily described by the induced free holes and electrons, and is located in the graphene sheet. On the other hand, the type and position of charges in the electrolyte requires a more elaborated description.…”

Carbon nanomaterials field-effect-transistor-based biosensors

“…Only very recently has the operation of graphene in aqueous electrolytes (Figure 6b) for use in biosensors and bioelectronics been reported by several groups. [77][78][79][80][81][82][83][84][85][86] For example, Ang et al 77 first demonstrated the use of solution-gated epitaxial graphene as a pH sensor. Ohno et al 78 reported on electrolyte-gated graphene field-effect transistors for detecting pH and protein adsorption.…”

“…81 These reports already confirm the potential of graphene for sensing in aqueous electrolytes, however, detailed understandings of the graphene/ electrolyte interface and the effect of the electrolyte on the electronic transport in graphene are still lacking. To address these issues, Dankerl et al 82 developed a facile method for the scalable fabrication of graphene FET arrays and provided a comprehensive characterization of operation of these devices in aqueous electrolytes. By using in-solution Hall-effect measurements and taking into account the microscopic structure of water at the interface, they demonstrated that charge carrier mobilities and concentrations as a function of electrolyte gate potential can be directly determined.…”