Nanoelectronic devices based on functionalized nanocarbon materials are emerging as a promising technology for lab-on-a-chip, molecular-scale biosensors. In this presentation, I will present the design and operation of such sensors to detect and monitor DNA sequences. Carbon nanotubes or graphene channels are immersed in microfluidics and functionalized with single-stranded DNA. Hybridization of complementary sequences with the tethered DNA induces a specific change in the electrical conductance of the devices. I will present recent experiments based on this design to detect specific DNA sequences and to monitor their dynamic interactions with single-molecule resolution.