Thermal broadening in graphene-based electromechanical nanosensors and molecular electronic junctions.

New nanoscale devices and protocols for molecular detection in aqueous environments at room temperature are highly desirable for their potential application in DNA sequencing and in vivo cell studies. Due to their electromechanical properties, graphene and other 2D materials provide a platform for electromechanical sensing under these conditions. We have investigated this idea by analyzing representative models. In particular, we have derived analytic expressions for the current, the electromechanical susceptibility, and signal-to-noise ratio. These expressions reveal the relative importance of thermal fluctuations, strain and geometric properties in the electromechanical response. Significantly, we find that as a result of the environmental fluctuations, electromechanical structures have an electron transmission function that follows a generalized Voigt profile, in close analogy to the inhomogeneous lineshapes found in spectroscopic and diffraction studies. These results allow us to formulate sensing protocols in terms of detector parameters, and give the fundamental operational principles for graphene deflectometry.