Voltammetric Electrochemical Detection of Concentration Changes in a Microfluidic Chip Is Delayed in Comparison to Amperometry

The time responses of two electrochemical methods, amperometry (AMP) and cyclic voltammetry (CV), used in a microchannel to detect the concentration variations of an outer-sphere redox species were compared. Overall, our results show that the temporal resolution of AMP is superior to the one of CV. As no secondary reaction (formation of chemical bounds, adsorption, etc.) can hinder the detection, this phenomenon was attributed to the instability of the diffusion layer in CV, filtering off the fast frequency components of the detected signal. This fact can have implications to improve electrochemical detection in microchannels, especially at fast flow rates.