Raman and Conductivity Analysis of Graphene for Biomedical Applications

Abstract

In this study, we present a comprehensive investigation of graphene’s optical and conductive properties using confocal Raman and a Drude model. A comparative analysis between experimental findings and theoretical predictions of the material’s changes and improvements as it transitioned from three-dimensional graphite is also presented and discussed. Besides spectral recording by Raman, which reveals whether there is a single, a few, or multi-layers of graphene, the confocal Raman mapping allows for distinction of such domains and a direct visualization of material inhomogeneity. Drude model employment in the analysis of the far-infrared transmittance measurements demonstrates a distinct increase of the material’s conductivity with dimensionality reduction. Other particularly important material characteristics, including carrier concentration and time constant, were also determined using this model and presented here. Furthermore, the detection of micromolar concentration of dopamine on graphene surfaces not only proves that the Raman technique facilitates ultrasensitive chemical detection of analytes, besides offering high information content about the biomaterial under study, but also that carbon-based materials are biocompatible and favorable micro-environments for such detection. Such information is valuable for the development of bio-medical sensors, which is the main application envisioned for this analysis.

Effects of Thermal Annealing on the Properties of Mechanically Exfoliated Suspended and On-Substrate Few-Layer Graphene

“…Also, the weak bands at around 1620 cm −1 , 1460 cm −1 , and 2930 cm −1 of the suspended thin graphene sheet are removed. The feature at 1460 cm −1 is close to an R-band feature observed by others around 1505 cm −1 which has been attributed to folding or bending in the graphene, which could be the result of the transfer process affecting the thin sample area more [26]. As it is removed here after annealing, it would suggest that the mechanical change in the graphene sheets has removed this feature.…”

Analysis of Carbon-Based Microelectrodes for Neurochemical Sensing

“…The characteristics of carbon fiber microelectrodes (CFMs) based biosensors for measuring extracellular concentrations of neurochemicals and other biological analytes, in real-time and with high accuracy, have been of continuous scientific interest for the past few decades [1,2,3,4,5,6,7,8,9]. A variety of electrochemical recording techniques have employed such sensors, including constant-potential amperometry and fast-scan cyclic voltammetry (FSCV) [10,11,12,13,14,15].…”

Improvement of structure and electrical conductivity of activated carbon by catalytic graphitization using N2plasma pretreatment and iron(iii) loading

“…32 The D-peak is related to the defective and disordered structure attributed to A 1g mode of sp 3 -hybridized carbon atoms in a cubic lattice, and the G-peak is assigned to E 2g mode of sp 2bonded carbon atoms in two-dimensional graphite sheets with the C-C stretching vibrations. 33 However, the G peak of PAC-0 apparently shis to a position with the higher wavenumber, resulting from small crystallites with little three-dimensional order. 9 In addition, one band at around 1150 cm À1 refers to a region with alicyclics and aliphatic chains of g (C]C), while the other at 1516 cm À1 is regarded as amorphous carbons with a singly broad and asymmetrical band.…”