We describe a new ultramicroelectrode fabrication technique that has allowed the preparation of conical Pt-Ir ultramicroelectrodes with radii of 0.5-10 μm. These electrodes have been characterized by scanning electron microscopy, cyclic voltammetry, and chronoamperometry. The smallest radii electrodes (r < 2 μm) exhibited diffusional behavior at times longer than 70 μs in accord with a hemispherical geometry, while larger radii electrodes exhibited diffusional behavior consistent with a conical geometry. A first-order mathematical approach to diffusion at conical surfaces has been developed to explain these results.
ASJC Scopus subject areas
- Analytical Chemistry