Electronic transport in DNA functionalized graphene sensors

TL;DR

This paper provides a theoretical analysis of electronic transport in DNA-functionalized graphene sensors, aligning with experimental data and enabling prediction of sensor responses for different DNA sequences.

Contribution

It introduces a NEGF-based theoretical framework to model time-dependent electronic transport in DNA-graphene sensors, accounting for vapor effects on charge distribution and interatomic distances.

Findings

Theoretical results match experimental observations.

Shift in Fermi level due to vapor adsorption is quantified.

Predictive capability for sensor responses based on DNA sequences.

Abstract

A theoretical understanding of the experimental electronic transport phenomena in gas sensors based on DNA functionalized graphene is presented by quantitatively investigating the time-dependent electronic transport in these devices using the nonequilibrium Green's function (NEGF) formalism and tight-binding approximation. The time-dependent zeroth and first order contributions to the current are calculated with derivations of the equation of motion and Dyson equation. The zeroth order contribution is identified as the time-dependent Landauer formula in terms of the slow time variable and the first order contribution is found to be small in this experiment. The current is explicitly calculated by deriving a formula for the transmission function and considering a form for the hopping integral which includes the effect of chemical vapors on the charge distribution of the carbon atoms and the nearest-neighbor carbon-carbon distance $\rm a_{cc}$. Theoretical results are found in agreement with the experimental results. A shift in the Fermi level ($\rm \varepsilon_f$) is calculated, which is a result of shift in the Dirac point due to adsorption of vapors on the DNA functionalized graphene. The work suggests that using the same values of change in $\rm a_{cc}$ due to the four DNA bases for a specific target vapor, the theoretical values of the current response can be predicted for different DNA sequences leading to the application of the graphene sensors as a DNA analyser.