Chemical sensing with graphene: A quantum field theory perspective

We studied theoretically the effect of a low concentration of adsorbed polar molecules on the optical conductivity of graphene, within the Kubo linear response approximation. Our analysis is based on a continuum model approximation that includes up to next to nearest neighbors in the pristine graphene effective Hamiltonian, thus extending the field-theoretical analysis developed in Refs.[1,2]. Our results show that the conductivity can be expressed in terms of renormalized quasiparticle parameters $\tilde{v}_F$, $\tilde{M}$ and $\tilde{\mu}$ that include the effect of the molecular surface concentration $n_{dip}$ and dipolar moment $\boldsymbol{\mathcal{P}}$, thus providing an analytical model for a graphene-based chemical sensor.