Miniaturization and exact positioning of needle-type electrodes opens new ways for the visualization of chemical and biochemical activity on surfaces. In scanning electrochemical microscopy (SECM) a needle-type ultramicroelectrode is positioned in close proximity to a surface of interest, and the Faraday current caused by the redox conversion of a free-diffusing redox mediator is used to visualize with high lateral resolution the electrochemical activity. The tutorial lecture will present the basic considerations concerning SECM in constant-height and constant-distance scanning together with the different operation modes of SECM such as feedback mode, generator-collector mode.

Using different examples from material sciences and biological applications the successful application of SECM and constant-distance mode SECM will be demonstrated:
- fabrication of different types of needle-type nanoelectrodes and high-
resolution SECM imaging
- fabrication of feedback-independent nanoelectrodes for high-resolution
imaging in pure generator-collector arrangements
- fabrication of combined dual electrode tips and SECM imaging in
microdroplets
- studies on the dissolution of CaCO₃ crystal in aqueous solution using a Ca²⁺-selective capillary-type liquid-membrane potentiometric sensor
- application of constant-distance mode SECM for local detection of
signaling molecules released from adherently growing biological cells
- alternating-current SECM as a tool for imaging of local corrosion
phenomena.

The author is grateful to the present and former coworkers in the research group who contributed to the development of SECM namely Christine Kranz, Andreas Hengstenberg, Bernardo Ballesteros Katemann, Thomas Erichsen, Mathieu Etienne, Albert Schulte, Luciana Pitta, Nizam Diab, Sonnur Isik, Sascha Belger, Florin Turku, Marcus Mosbach.