Graphene deflectometry for sensing molecular processes at the nanoscale

TL;DR

This paper proposes a graphene-based deflectometry sensor capable of detecting ultra-weak, fast molecular processes at room temperature by translating nanoscale deflections into measurable electronic signals, overcoming thermal noise limitations.

Contribution

It introduces a theoretical framework for using suspended graphene nanoribbons as sensitive force transducers for molecular sensing at room temperature.

Findings

Intrinsic sensitivity less than 7 fN/√Hz.

Able to detect fast, weak molecular processes.

Effective in aqueous environments.

Abstract

Single-molecule sensing is at the core of modern biophysics and nanoscale science, from revolutionizing healthcare through rapid, low-cost sequencing to understanding various physical, chemical, and biological processes at their most basic level. However, important processes at the molecular scale are often too fast for the detection bandwidth or otherwise outside the detection sensitivity. Moreover, most envisioned biophysical applications are at room temperature, which further limits detection due to significant thermal noise. Here, we theoretically demonstrate reliable transduction of forces into electronic currents via locally suspended graphene nanoribbons subject to ultra-low flexural deflection. The decay of electronic couplings with distance magnifies the effect of the deflection, giving rise to measurable electronic current changes even in aqueous solution. Due to thermal fluctuations, the characteristic charge carrier transmission peak follows a generalized Voigt profile, behavior which is reflected in the optimized sensor. The intrinsic sensitivity is less than 7 fN/$\sqrt{\mathbf{Hz}}$, allowing for the detection of ultra-weak and fast processes at room temperature. Graphene deflectometry thus presents new opportunities in the sensing and detection of molecular-scale processes, from ion dynamics to DNA sequencing and protein folding, in their native environment.