The pulse-mode scanning ion conductance microscope (PMSICM) is a tool to image living cells in cell culture. For SICM imaging common patch-clamp-type glass electrodes can be used. When the electrolyte filled electrode approaches an insulating surface submerged in electrolyte solution the access resistance changes and conductivity decreases. This change in resistance occurs prior to an actual physical contact of the cell with the electrode.

The technique was first developed by Hansma and coworkers (Science, 1989) and first applied by Korchev et al. (J. Microscopy, 1997) to scan living cells and refined to image entire cell bodies with overhanging membrane areas by introducing a backstep mode as reported in Mann et al. (J. Neurosc. Methods, 2002).

Here we show that the method can be used for long term observations of cell somata in cell culture. Due to its contact-free scanning property PM-SICM allows the imaging of cell surfaces in the range of several hours and as a consequence allows one to detect changes in cell shape and cell movement by comparing successive scans.