Fig. 1. (Color online) (a) Schematic diagram of GFET. (b) The Image of the GFET and zoomed-in chip. (c) The fabrication process of the biosensor on graphene surface.

Fig. 2. (Color online)I_ds–V_g transfer characteristic curve in (a) PBS solution, (b) fluidartificial saliva, (c) bovine serum fluid, and (d) artificial urine.

Fig. 3. (Color online) (a) Schematic illustration of the detection mechanism. (b) Schematic illustration of the change of Dirac cone causing by electron doping.

Fig. 4. (Color online) GFET sensor devices in PBS solution detect Met-BSA in real time. (a)I_ds–t output characteristic curve. (b) Normalized treatment. (c) Response time. (d) Schematic diagram for Met detection in biological fluids using the GFET.