Electrochemical Detection Based on Redox Cycling Using Interdigitated Microarray Electrodes at µL/min Flow Rates

Abstract

The in¯uence of convection on the degree of redox cycling at interdigitated microarray electrodes in a¯ow system was investigated in the end column detection mode for¯ow rates below 20 mL/min. It was found that the degree of redox cycling increased with decreasing¯ow rates and values of 2.9 and 2.2 were obtained for a¯ow rate of 2 and 20 mL/min, respectively, using photolithographically fabricated interdigitated arrays consisting of 140 microbands separated by 6 mm. The obtained degrees of redox cycling were lower than the value of 4.4 obtained in a stationary solution in the batch mode as a result of a decreased collection ef®ciency between adjacent microbands and a relatively low conversion ef®ciency at each microband in the presence of the¯ow. It is shown that a collection ef®ciency of more than 90 % is needed to produce an order of magnitude increase in the current due to redox cycling in a stationary solution. When using a microarray electrode consisting of 280 microbands in a thin layer¯ow cell, a conversion ef®ciency of close to 100 % could be obtained at¯ow rates below 1 mL/min. In the latter case, a signi®cantly larger¯ow rate dependence of the current was found compared to that for a single microband electrode.

Electrochemically controlled solid-phase microextraction and preconcentration using polypyrrole coated microarray electrodes in a flow system

“…Using this set-up the collection efficiency was estimated to be about 80% based on previously published data. 23 To investigate if the size of the polymer coated microband electrode was large enough to extract a detectable amount of chloride ions, within a reasonable amount of time, a high analyte concentration of 5 mM chloride was initially used. In these experiments, a 5 mM sodium chloride solution was also used as the electrolyte in the bulk solution.…”

Theoretical treatment and computer simulation of microelectrode arrays

“…(13) and (14). From the values b determined by the finite-element method for MEAs, one calculates a = 2.56 and 1.96 for IDAs with w/w el = 1.5 and 2, respectively.…”

“…Therefore, the relationship between the geometrical parameters of the interdigitated microelectrode arrays and the redox cycling efficiency has been extensively investigated in both stationary [8][9][10] and flow systems [11][12][13].…”

Differential cyclic voltammetry - a novel technique for selective and simultaneous detection using redox cyling based sensors

“…Most papers on RC make use of an interdigitated array electrode [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. With such an electrode a RC amplification of up to ~65 times is reported in bulk [2].…”