Band microelectrodes

Background current, 21, 65 Background subtraction, 40, 106 Bacteria electrode, 182 Band microelectrodes, 130, 135 Beryllium, 82 Bienzyme electrodes, 175 Biocatalytic devices, 172 Biological recognition, 171 Biosensors, 50, 171 Bipotentiostat, 106 Blood electrolyte, 165 Boltzmann equation, 19 Brain analysis, 40, 116 Butler-Volmer equation, 14... 

The forward and reverse currents i/rf and i//( of the square wave voltammograms corresponding to Fig. 7.5c are shown in Fig. 7.6a for microelectrodes of the four electrode geometries considered. From these curves, it can be seen that both currents present a sigmoidal shape and they are separated by 2Esw in the case of spheres and discs. This behavior clearly shows that the steady state has been attained. On the other hand, in the case of cylinders and bands, y/f and i/// show a transient behavior under these conditions. From Fig. 7.6b, c, it can be verified that a decrease in the radius, ((w/2) = rc = 0.1 pm) and that of both radius and frequency (Fig. 7.6c, (w/2) = rc = 0.1 pm and/= 10 Hz) do not lead to a stationary SWV response at cylinder and band microelectrodes. 

Fig. 5 A cartoon illustrating development of a hemi-cylindrical diffusion profile near a band microelectrode in 3D, and a hemi-circular diffusion profile near a line electrode in 2D experiments. The two types of diffusion processes are analogous. Reduction of dimensionality converts the product of the electrode length (/) and a reagent bulk concentration (C ) appearing in the cylindrical diffusion equations into the surface concentration (T ) C / F (see text and Ref 46).

Combellas C, Fuchs A, Kanoufi F (2004) Scanning electrochemical microscopy with a band microelectrode theory and application. Anal Chem 76 3612-3618... 

Szabo A, Cope DK, TaUman DE, Kovach PM, Wightman RM (1987) Chronoamperometric current at hemicylinder and band microelectrodes theory and experiment. J Electroanal Chem 217 417 23... 

Amatore C, Oleinick A, Svir 1 (2004) Simulation of diffusion-convection processes in microfluidic channels equipped with double-band microelectrode assemblies approach through quasi-conformal mapping. Electrochem Commun 6 1123-1130... 

Szabo, A. Cope, D. Tallman, D. Kovach, D. Wightman, P. Chronoamperometric current at hemicylin-der and band microelectrodes—Theory and experiment. J. Electroanal. Chem. 1987, 217,417-423. 

FIGURE 17.42 SECM-optical microscopy images of band microelectrodes (IDA electrode) acquired using an optical fiber/microelectrode tip in the fixed height mode. Simultaneously obtained (a) electrochemical and (b) optical images d=l pm over the bands). Scan speed was 1 pm/s. Fiber apex (r )= 1.75 pm. (Reproduced with permission from Lee, Y. and Bard, A.J., Fabrication and characterization of probes for combined scanning electrochemical/optical microscopy experiments, Anal. Chem., 74, 3626-3633, 2002. Copyright 2002 American Chemical Society.)... 

A more recent and very useful review [5] considers voltammetric/amperometric microelectrode arrays, their construction techniques, and various approaches to surface modification. This review includes disk and band microelectrodes with regular or random spacings between array elements. Several bioanalytical apphca-tions, including nucleic acid and protein detection, are included. 

A band microelectrode is a two-dimensional diffusion system in which the length of the electrode is very much larger than the width. The coordinate system used to treat the diffusion problem at this geometry is shown in Fig. 15.8 and... 

Figure 7. Linear sweep voltammogram of cytochrome c at (a) PySSPy modified gold microelectrode array and (b) Tin doped In203 band microelectrode in 0.2 M ionic strength of tris/cacodylic acid buffer at scan rate of 10 mVs-. ...

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