Optically Transparent Thin-Film Electrode Chip for Spectroelectrochemical Sensing

Abstract

A novel microfabricated optically transparent thin-film electrode chip for fluorescence and absorption spectroelectrochemistry has been developed. The working electrode was composed of indium tin oxide (ITO); the quasi-reference and auxiliary electrodes were composed of platinum. The stability of the platinum quasi-reference electrode was improved by coating it with a planar, solid state Ag/AgCl layer. The Ag/AgCl reference was characterized with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cyclic voltammetry measurements showed that the electrode chip was comparable to a standard electrochemical cell. Randles-Sevcik analysis of 10 mM K[Fe(CN)] in 0.1 M KCl using the electrode chip gave a diffusion coefficient of 1.59 × 10 cm/s, in comparison to the value of 2.38 × 10 cm/s using a standard electrochemical cell. By using the electrode chip in an optically transparent thin-layer electrode (OTTLE), the absorption based spectroelectrochemical modulation of [Fe(CN)] was demonstrated, as well as the fluorescence based modulation of [Ru(bpy)]. For the fluorescence spectroelectrochemical determination of [Ru(bpy)], a detection limit of 36 nM was observed.

Electrochemistry and Spectroelectrochemistry of the Pu (III/IV) and (IV/VI) Couples in Nitric Acid Systems

“…However, by utilizing electrochemistry and spectroscopy to simultaneously characterize Pu in nitric acid solution, a more complete picture of Pu behavior can be realized. This combined approach to characterizing species, or spectroelectrochemistry, has been described for applications to other complex systems as well as sensor development . When applied to Pu, it can be used to more accurately probe the sensitivity of the Pu (III/IV) couple to acid strength.…”

Spectroelectrochemical Sensing: Current Trends and Challenges

“…As is well‐known, molecular fluorescence spectroscopy is an analytical technique characterized by a very high sensitivity, usually significantly higher than UV/Vis absorption spectroscopy, because it is relatively easy to distinguish dark background from low levels of light . Additionally, it can have an exceptional selectivity by using specific fluorescent molecular sensors .…”

“…In general, there is a difference in either excitation or emission spectra of analyte and interfering compounds. In addition, the length of the optical pathway is not so important in fluorescence as in absorption techniques .…”

“…A simple thin‐layer cell based on an SPE has been used to determine tris(2,2’‐bipyridyl)dichlororuthenium(II) complex with a limit of detection of 36 nM, demonstrating the high sensitivity of PL‐SEC .…”

Polystyrene Microspheres Coupled with Hybridization Chain Reaction for Dual-Amplified Chemiluminescence Detection of Specific DNA Sequences

“…Up to now, a broad range of strategies such as optical (fluorescence [8][9][10][11], chemiluminescence (CL) [12][13][14][15][16], colorimetry [17,18], dynamic light scattering [19] surface plasmon resonance [20,21], etc. ), piezoelectric [22] and electronic transduction techniques [23,24] have been developed.…”