Gate-Modulated Graphene Quantum Point Contact Device for DNA Sensing

In this paper, we present a computational model to describe the electrical response of a constricted graphene nanoribbon (GNR) to biomolecules translocating through a nanopore. For this purpose, we use a self-consistent 3D Poisson equation solver coupled with an accurate three-orbital tight-binding model to assess the ability for a gate electrode to modulate both the carrier concentration as well as the conductance in the GNR. We also investigate the role of electrolytic screening on the sensitivity of the conductance to external charges and find that the gate electrode can either suppress or enhance the screening of biomolecular charges in the nanopore depending on the value of its potential. Translocating a double-stranded DNA molecule along the pore axis imparted a large change in the conductance at particular gate voltages, suggesting that such a device can be used to sense translocating biomolecules and can be actively tuned to maximize its sensitivity.