Electrochemical Behavior of Reversible Redox Species at Interdigitated Array Electrodes with Different Geometries: Consideration of Redox Cycling and Collection Efficiency

Interdigitated array (IDA) electrodes with different geometric parameters have been fabricated by a lithographic technique and applied to cyclic voltammetric and chronoamperometric measurements of reversible redox species. The collection efficiency Is dependent on the average diffusion length of W./4 + gap, where W. is the band electrode width in the IDA. The number of redox cycles rapidly increases by decreasing W./4 + gap and is closely related to collection efficiency. The difference In species diffusion constant had little effect on the collection efficiency and redox cycling. The high redox cycling and collection efficiency of the IDA's allowed electrochemical measurements to be highly sensitive (10 nmol/dm³), with a high signal to noise ratio and a wide dynamic range (10 nmol/dm³ to 1 mmol/dm³). Chronoamperometric measurement has been performed In a four-electrode configuration where step potential was applied to the generator electrode and constant potential was applied to the collector electrode in the IDA. The generator current reached steady state within a hundred milliseconds and the collector current was not affected by charging. With the IDA, fast sweep cyclic voltammetry with no observable charging current has been also demonstrated.