  Scalable production of all-electronic DNA biosensors with high sensitivity
and selectivity is a critical enabling step for research and applications
associated with detection of DNA hybridization. We have developed a scalable
and very reproducible (> 90% yield) fabrication process for label-free DNA
biosensors based upon graphene field effect transistors (GFETs) functionalized
with single-stranded probe DNA. The shift of the GFET sensor Dirac point
voltage varied systematically with the concentration of target DNA. The
biosensors demonstrated a broad analytical range and limit of detection of 1 fM
for 60-mer DNA oligonucleotide. In control experiments with mismatched DNA
oligomers, the impact of the mismatch position on the DNA hybridization
strength was confirmed. This class of highly sensitive DNA biosensors offers
the prospect of detection of DNA hybridization and sequencing in a rapid,
inexpensive, and accurate way.
