Hopping Mode SICM
A breakthrough in SICM came with the introduction of hopping mode¹. This mode of operation now enables the imaging of almost any feature under 100 µm in height. The diagram below shows how hopping mode (b) enables the operator to image a sample without the risk of collision with taller features. Instead of performing a raster scan measurement of the sample (a), the technique now retracts the pipette to a user-defined height before moving along to the next pixel. This takes into account the fact that the sensitive area of the pipette is at its very tip.
The images above (c, d: living neural network; e,f : fixed organ of corti cells) show how raster scanning SICM can collide with certain features during measurement - in these cases, certain live processes and the cell body are affected (c, e). However, with hopping mode SICM (d, f) even very fine delicate processes remain intact throughout the course of the scan.
¹ Novak, P., Li, C., et al. (2009). "Nanoscale live-cell imaging using hopping probe ion conductance microscopy." Nature Methods, doi:10.1038/nmeth.1306
