Interpretation of electrochemical noise generated by multiple electrodes

The electrochemical potential and current noise generated by an array of galvanically coupled electrodes have been analysed. The individual currents flowing through each electrode are measured simultaneously with the potential of the array. For each electrode, the apparent noise resistance, R n*, is determined from the square root of the potential variance divided by the individual current variance. Depending on the relative noise levels and resistances of electrode n and the remaining n-1 electrodes, R n* may approach closely to the true noise resistance of electrode n, R n, be proportional to R n, or be unrelated to R n. The analysis is facilitated by the introduction of "virtual electrodes", corresponding to a convenient sub-array of real electrodes, and obtained by mathematical manipulation of the individual currents in the time or frequency domain. By using this approach, the validity of the assumptions on the relative magnitude of the noise sources and electrode resistances that are often necessary to evaluate R n can be partially or completely verified. For example, the electrochemical noise data recorded from four identical electrodes and from two dissimilar couples of identical electrode are discussed. ©2012 by NACE International.