Facilitated tip-positioning and applications of non-electrode tips in scanning electrochemical microscopy using a shear force based constant-distance mode.

In scanning electrochemical microscopy (SECM) a microelectrode is usually scanned over a sample without following topographic changes (constant-height mode). Therefore, deconvolution of effects from distance variations arising from non-flat sample surface and electrochemical surface properties is in general not possible. Using a shear force-based constant distance mode, information about the morphology of a sample and its localized electrochemical activity can be obtained simultaneously. The setup of the SECM with integrated constant-distance mode and its application to non-flat or tilted surfaces, as well as samples with three-dimensional surface structures are presented and discussed. The facilitated use of non-amperometric tips in SECM like enzyme-filled glass capillaries is demonstrated.