Phononics of Graphene Interfaced with Flowing Ionic Fluid: An Avenue for High Spatial Resolution Flow Sensor Applications.
basic_science · Level V
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- Record sourced from PubMed, PMID 33834760.
- Also identified by DOI 10.1021/acsnano.1c00020.
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Abstract
While ionic flow over graphenic structures creates electromotive potential, there is a need to understand the local carrier density induced in graphene without any electrode-induced Fermi-level pinning. Here, we show the electrolyte-flow induced localized doping in graphene <i>via</i> inspecting its Raman phononic energy. Graphene's Fermi energy level has a logarithmic dependence to the flow velocity over 2 orders of magnitude of velocity (∼100 μm s<sup>-1</sup> to 10 mm s<sup>-1</sup>). A theoretical model of the electric double layer (EDL) during ionic transport is used to correlate the Fermi level of graphene with the flow rate and the electronic structure (HOMO-LUMO levels) of the ionic species. This correlation can allow us to use graphene as a reliable, non-invasive, optical flow-sensor, where the flow rates can be measured at high spatial resolution for several lab-on-a-chip applications.