Fabrication and Characterisation of the Graphene Ring Micro Electrode (GRiME) with an Integrated, Concentric Ag/AgCl Reference Electrode

Abstract

We report the fabrication and characterisation of the first graphene ring micro electrodes with the addition of a miniature concentric Ag/AgCl reference electrode. The graphene ring electrode is formed by dip coating fibre optics with graphene produced by a modified Hummers method. The reference electrode is formed using an established photocatalytically initiated electroless deposition (PIED) plating method. The performance of the so-formed graphene ring micro electrodes (GRiMEs) and associated reference electrode is studied using the probe redox system ferricyanide and electrode thicknesses assessed using established electrochemical methods. Using 220 μm diameter fibre optics, a ∼15 nm thick graphene ring electrode is obtained corresponding to an inner to outer radius ratio of >0.999, so allowing for use of extant analytical descriptions of very thin ring microelectrodes in data analysis. GRiMEs are highly reliable (current response invariant over >3,000 scans), with the concentric reference electrode showing comparable stability (current response invariant over >300 scans). Furthermore the micro-ring design allows for efficient use of electrochemically active graphene edge sites and the associated nA scale currents obtained neatly obviate issues relating to the high resistivity of undoped graphene. Thus, the use of graphene in ring microelectrodes improves the reliability of existing micro-electrode designs and expands the range of use of graphene-based electrochemical devices.

Deoxygenation of graphene oxide using household baking soda as a reducing agent: a green approach

“…38 This morphological difference between the folded edge of GO and sharp edge of SRGO demonstrate that the household baking soda can play an important role to convert the GO into functional graphene. 66 The enhancement of atomic oxygen in GO revels the successful oxidation of graphite. Fig.…”

“…13b), the atomic weight percentage of carbon and oxygen were found to be 58.4% and 38.9%, respectively. 66 The enhancement of atomic oxygen in GO reveals the successful oxidation of graphite. Noticeably, the elimination of impurities other than trace amounts of S (2.7 atomic weight percentage) conrms that the GO precursor prepared by modied hummer method is pure.…”

Nanoporous gold peel-and-stick biosensors created with etching inkjet maskless lithography for electrochemical pesticide monitoring with microfluidics

“…Bleach is a concentrated sodium hypochlorite solution which effectively chlorinates silver as reported in literature. [70][71][72] After chlorination, the luster/color of the silver changed to a dull grey indicating the formation of a AgCl layer (Fig. 3a).…”

On-Line Monitoring the Growth of E. coli or HeLa Cells Using an Annular Microelectrode Piezoelectric Biosensor

“…We optically polished the glass surface and cleaned it with a piranha solution (1:3 (v/v) 30% H 2 O 2 /H 2 SO 4 ) for 5 min. Then, the glass surface was sonicated in acetone and double-distilled water (each for 3–5 min) individually and dried under a nitrogen flow [13,14,15]. A 20-nm-thick Cr adhesion layer was first sputtered directly onto the glass surface via radio frequency magnetron sputtering, followed by a 200 nm gold layer as the microelectrode material on the Cr layer to enhance the adhesion of the Au layer on the glass substrate.…”