Scanning electrochemical microscopy: Diffusion controlled approach curves for conical AFM-SECM tips

The diffusion controlled response of conical AFM-SECM probes is presented. Accurate expressions are given which describe the dependence of the probe current on the tip radius and aspect ratio, insulating sheath radius and tip–substrate distance for positive feedback and hindered diffusion. A procedure is proposed to determine the tip dimensions from the experimental approach curves.

► Diffusion controlled approach curves at conical AFM-SECM tips
► Equations account for aspect ratio, insulation radius and tip–substrate distance.
► Detailed fitting guidelines with a global fit to the positive and negative feedback approach curves
► Determination of geometric parameters from experimental approach curves