Boosting DNA Recognition Sensitivity of Graphene Nanogaps through Nitrogen Edge Functionalization

One of the challenges for next generation DNA sequencing is to have a robust, stable, and reproducible nanodevice. In this work, we propose how to improve the sensing of DNA nucleobase using functionalized graphene nanogap as a solid state device. Two types of edge functionalization, namely, either hydrogen or nitrogen, were considered. We showed that, independent of species involved in the edge passivation, the highest-to-lowest order of the nucleobase transmissions is not altered, but the intensity is affected by several orders of magnitude. Our results show that nitrogen edge tends to p-dope graphene, and most importantly, it contributes with resonance states close to the Fermi level, which can be associated with the increased conductance. Finally, the translocation process of nucleobases passing through the nanogap was also investigated by varying their position from a certain height (from +3 to −3 Å) with respect to the graphene sheet to show that nitrogen-terminated sheets have enhanced sensitivity, as moving the nucleobase by approximately 1 Å reduces the conductance by up to 3 orders of magnitude

Highly Sensitive and Selective Gas Detection Based on Silicene

Recent advances in the fabrication of silicene devices have raised exciting prospects for practical applications such as gas sensing. We investigated the gas detection performance of silicene nanosensors for four different gases (NO, NO₂, NH₃, and CO) in terms of sensitivity and selectivity, employing density functional theory and nonequilibrium Green’s function method. The structural configurations, adsorption sites, binding energies and charge transfer of all studied gas molecules on silicene nanosensors are systematically discussed in this work. Our results indicate that pristine silicene exhibits strong sensitivity for NO and NO₂, while it appears incapable of sensing CO and NH₃. In an attempt to overcome sensitivity limitations due to weak van der Waals interaction of those latter gas molecules on the device, we doped pristine silicene with either B or N atoms, leading to enhanced binding energy as well as charge transfer, and subsequently a significant improvement of sensitivity. A distinction between the four studied gases based on the silicene devices appears possible, and thus these promise to be next-generation nanosensors for highly sensitive and selective gas detection