Forced convection during scanning electrochemical microscopy imaging over living cells: Effect of topographies and kinetics on the microelectrode current

Scanning electrochemical microscopy (SECM) is increasingly applied to study and image live cells. To reduce the overall analysis time during live cell SECM measurements and maintain cell viability, the microelectrode scan rate can be increased. The use of increasing microelectrode scan rates is challenging because our understanding of the downstream convection effects is tied to the ill-defined topography of the imaged live cells. The present study investigates the effect of forced convection on the microelectrode current during SECM imaging of live cells, model non-planar substrates and planar surfaces. Experimentally, we demonstrate that during constant height imaging, the normalized peak current observed during line scans on all three substrates scales linearly with the microelectrode velocity. This quasi-linear relationship is corroborated by finite element simulations of non-planar substrates, which further reveal that the slope is closely related to the electrochemical activity of the substrate.