Figure 2

Figure 2: Graphene transistor, 9×60 mm2 in size, a) Drain-source current change   with electrolyte gating voltage Vg in 10 mM phosphate buffer,   drain-source voltage VDS=50mV. b) Dirac point shift with pH. c) Drain-source current versus time   data for values of pH between 10 and 3.5 with Vg=0.4V and VDS=10mV.