Analytical Characterization of Microlithographically Fabricated Iridium-Based Ultramicroelectrode Arrays

Abstract

The analytical performance of several mercury-coated iridium ultramicroelectrode arrays (IrUMEAs) was studied using square wave anodic stripping voltammetry (SWASV) for determination of cadmium in a pH 4.5 acetate buffer. The microlithographically fabricated IrUMEAs consisted of either 20 or 25 individual disk shaped UMEs, each 10 mm in diameter. The insulating layer utilized in the fabrication process was either silicon dioxide (5000 Å ) or silicon nitride (1500 Å or 2500 Å ). Calibration plots demonstrated good linearity for cadmium from 0-100 ppb. Standard deviations, detection limits, and correlation coefficients were calculated to determine the stability and reproducibility of the IrUMEAs. Repetitive cycles of depositing and stripping Hg at the IrUMEA surface resulted in increased distortion and loss of the SWASV signal. Atomic force microscopy revealed a subtle transformation in the IrUMEA surfaces.

Fractionation and Speciation of Trace Elements in Soil Solution

“…Several studies report the development of Hg-plated Ir-based microelectrode array sensors for the determination of trace elements using square wave anodic stripping voltammetry, SWASV [129,[135][136][137]. Specifically in soil science, microelectrode arrays have already been used in combination with ASV for on-site analysis of arsenic (As 3þ ) in groundwater.…”

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 .…”

Microelectrode Arrays and Microfabricated Devices in Electrochemical Stripping Analysis

“…Iridium is one of the most used materials for MEAs [27,28,30,31,34,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55]. This is mainly due to the fact that it is the best metallic supporting material for electrodeposited mercury coatings (either microdrop or film electrodes) [15], because of the extremely low solubility of Ir in Hg (<10 -6 wt%) [36].…”