Microfabricated Recessed Microdisk Electrodes:  Characterization in Static and Convective Solutions

Abstract

Construction and characterization of microfabricated recessed microdisk electrodes (RMDs) of 14- and 55-μm diameters and 4-μm depth are reported. For evaluation of electrode function, both faradaic current in Ru(NH(3))(6)(3+)/KNO(3) solution and charging current in KNO(3) solution were measured with cyclic voltammetry. The experimental maximum current was measured and compared to calculated values, assuming radial and linear diffusion. A model for diffusion to a RMD best matches the behavior of the 14-μm RMD, which has a larger depth-to-diameter ratio than the 55-μm RMD. At fast scan rates (204 V s(-)(1)), where linear diffusion should dominate, there are large deviations from the linear diffusion model. Uncompensated resistance and overcorrection for background current contribute to this deviation. The dependence of capacitance on scan rate of the RMDs was found to be similar to that of a macroelectrode, indicating good adhesion between the insulator and the electrode. Chronoamperometry of Ru(NH(3))(6)(3+) in KNO(3) in both static and stirred solutions was performed using the RMDs and the current is compared to those from a 10-μm-diameter planar microdisk electrode (PMD). The signal-to-noise ratio of the 14-μm RMDs compared to the PMD is on average 4 times greater for stirred solutions. The 55-μm RMD exhibited no protection to convection of the stirred solution.

The stability of nonporous and macroporous titania thin films in aqueous electrolyte solutions

“…Eventually, the CV will look nearly identical to that obtained at a bare electrode (Scheme 1, bottom left). Such electrochemical responses have also observed for similar electrode configurations including nanoelectrode arrays, recessed microdisk electrodes, and nanodisk array electrodes [21][22][23]. In an experiment like this one, it is important that redox probes chosen have relatively fast kinetics and span different sizes and charges to evaluate if selective partitioning into the film takes place.…”

Métodos para fabricação de microeletrodos visando a detecção em microambientes

“…38,95,[125][126][127] O processo de litografia, utilizado na maioria dos casos de microfabricação, está baseado na transferência de uma cópia de um padrão mestre, de um determinado material, para um substrato sólido. Um exemplo é a fabricação de microeletrodos cônicos a partir do desgaste de um substrato de Si, seguido pela deposição de filmes finos de SiO 2 , Pt e Si 3 N 4 .…”

Electrochemical Immunoassay Detection of Bacillus Anthracis Protective Antigen

“…The VEG4X1™ microcavity array chips (called Figure 1A) containing 50-µm diameter cavities in an 4 x 1 array were fabricated using previously published methods with a slight change in size (33,34,35). The VEG 4X1™ are 1cm x 1.2 cm with contact pads that are 5 mm long and 1 mm wide located on one end of the chips.…”