Solution-gated epitaxial graphene as pH sensor.
A solution-gate field effect transistor (SGFET) has been fabricated on few-layer graphene (FLG). The ideally polarizable graphene/aqueous electrolyte interface allows the capacitive charging of the surface by hydroxyl (OH-) and hydroxonium ions (H3O+). The conductivity versus gate potential curve exhibits "V" shaped ambipolar transfer characteristics of graphene, with hole and electron mobilities of 3600 cm2/Vs and 2100 cm2/Vs, respectively. The shift of the negative gate potential with pH shows a supra-Nernstian response of 99 meV/pH. Our work points to the potential application of graphene in ultrafast and ultralow noise chemical or biological sensors.
Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
Priscilla Kailian
PK
Ang
Wei
W
Chen
Andrew Thye Shen
AT
Wee
Kian Ping
KP
Loh