Cs. Henry et I. Fritsch, Microfabricated recessed microdisk electrodes: Characterization in static and convective solutions, ANALYT CHEM, 71(3), 1999, pp. 550-556
Construction and characterization of microfabricated recessed microdisk ele
ctrodes (RMDs) of 14- and 55-mu m diameters and 4-mu m depth are reported.
For evaluation of electrode function, both faradaic current in RU(NH3)(6)(3
+)-/KNO3 solution and charging current in KNO3 solution were measured with
cyclic voltammetry. The experimental maximum current was measured and compa
red to calculated values, assuming radial and linear diffusion. A model for
diffusion to a RMD best matches the behavior of the 14-mu m RMD, which has
a larger depth-to-diameter ratio than the 55-mu m RMD. At fast scan rates
(204 V s(-1)), where linear diffusion should dominate, there are large devi
ations from the linear diffusion model. Uncompensated resistance and overco
rrection for background current contribute to this deviation. The dependenc
e of capacitance on scan rate of the RMDs was found to be similar to that o
f a macroelectrode, indicating good adhesion between the insulator and the
electrode. Chronoamperometry of RU(NH3)(6)(3+) in KNO3 in both static and s
tirred solutions was performed using the RMDs and the current is compared t
o those from a 10-mu m-diameter planar microdisk electrode (PMD). The signa
l-to-noise ratio of the 14-mu m RMDs compared to the PMD is on average 4 ti
mes greater for stirred solutions. The 55-mu m RMD exhibited no protection
to convection of the stirred solution.