Redox microelectrodes

What Is the Difference Between the Local Biofilm Potential and Redox Potential Recently, we introduced the concept of the local biofilm potential and compared it to redox potential [45]. In that study, we showed that there was a difference between the potential measured with a redox microelectrode and that... 

Small semiconductor particles also act like microelectrodes upon illumination. Electrons and positive holes are created in the particles which initiate redox reactions. The charge carriers may also recombine and emit fluorescence light. Reaction with a solute leads to quenching of the fluorescence. 

Figure 4 shows what is known to date about the standard potential of the silver microelectrode as a function of the agglomeration number n f For n = 1, i.e. the redox system... 

Cells, respectively human biopsies suspended in medium, are filled into the microchamber via a porthole. p02 measurements are performed with polarographic microelectrodes, registering redox-processes at the electrode tip. 

Metal/metal oxides are the materials of choice for construction of all-solid-state pH microelectrodes. A further understanding of pH sensing mechanisms for metal/metal oxide electrodes will have a significant impact on sensor development. This will help in understanding which factors control Nemstian responses and how to reduce interference of the potentiometric detection of pH by redox reactions at the metal-metal oxide interface. While glass pH electrodes will remain as a gold standard for many applications, all-solid-state pH sensors, especially those that are metal/metal oxide-based microelectrodes, will continue to make potentiometric in-vivo pH determination an attractive analytical method in the future. 

Bard AJ, Crayston JA, Kittlesen GP, Shea TV, Wrighton MS (1986) Digital simulation of the measured electrochemical response of reversible redox couples at microelectrode arrays consequences arising from closely spaced ultramicroelectrodes. Anal Chem 58 2321-2331... 

Recently, several molecule-based microelectrochemical devices have been developed by the Wrighton group.(14.15.21-22) A microelectrode array coated with poly(I) results in a microelectrochemical transistor with the unique characteristic that shows "turn on" in two gate potential, Vq, regimes, one associated with the polythiophene switching from an insulator to a conductor upon oxidation and one associated with the v2+ + conventional redox centers. 

In the SECM measurement (Figure 18), a small microelectrode (typically a metal or carbon electrode) is rastered across the surface of interest, and the current resulting from a Faradaic reaction is mea-sured. 220 q-j g experiment is arranged such that the tip current is proportional to the local concentration of a redox species, which in turn may reflect molecular transport rates within a porous matrix (Figure ISa) or the electron-transfer activity at an electrode (Figure 18b). 

For clusters of higher nuclearity too, the kinetic method for determining the redox potential °(M]] /M ) is based on electron transfer, for example, from mild reductants of known potential which are used as reference systems, towards charged clusters M](. [31] Note that the redox potential differs from the microelectrode potential M /M ) by the... 

The determination of ammonium, arsenic, thiosulfate, allyl alcohol, and iodide has been achieved with a bromine redox mediator. Tomcik etal. [156] employ interdigitated microelectrodes at which bromine is generated at one set of electrodes and collected at a second set of electrodes. The reaction of the bromine with the analytes allows quantitative determination down to a micromolar level. 

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