Detection of DNA by graphene-on-silicon FET structures simultaneously at DC and 101 GHz

Two graphene-silicon field-effect transistor samples are characterized as a biological sensor of single-stranded DNA at DC and 101 GHz. In the first sample the 13-mer DNA is detected at DC and 101 GHz at three different molarities: 0.01, 1.0 and 100 nM. In the second sample it is so detected at only 1.0 nM but under progressive dilution by de-ionized water. In both cases, the mechanism for detection appears to be the same: (1) at DC it is the DNA-induced decrease in sheet conductance, and (2) at 101 GHz it is a correlated decrease in RF sheet conductance and the associated increase in 101-GHz transmission through the GFET acting as an optical etalon.