Electrical detection of solution pH, protein adsorption and specific biomolecules were demonstrated by using graphene
field-effect transistors (G-FETs). The monolayer graphene flakes were used as channel, which were obtained by
conventional mechanical exfoliation from bulk graphite. The transport characteristics shifted to the positive voltage
direction with increasing solution pH. The drain current changed by desorption of the charged protein. Moreover, we
immobilized aptamers on the graphene surface. As a result, specific immunoglobulin sensing can be carried out using
aptamer-modified G-FETs. These results strongly suggested that the G-FETs have high potentials for chemical and
DNA hybridization has sensitively been detected using carbon nanotube field-effect transistors (CNTFETs) in real time. After full-complementary DNA introduction, the source-drain current gradually increased while monitoring in real time. Full-complementary DNA with concentration as low as 1 fmol/L solution could be effectively detected. Our CNTFET-based biochip is a promising candidate for the development of an integrated, high-throughput, multiplexed DNA biosensor for medical, forensic and environmental diagnostics.