In electron microscopy samples are typically studied by an electron beam in vacuum which ideally requires samples to be electrically conductive and stable in vacuum.

In scanning electron microscopy (SEM) the sample surface is studied which can require coating with a conductive layer (sputter or evaporation coating) or removal of organic surface contamination (plasma cleaning or UV cleaning). Various techniques for cutting, grinding, polishing or lapping is used for hard materials. Broad ion beams (BIB) are used to cut or polish samples. Focused ion beams (FIB, FIB/SEM) are used to extract samples at required sites (micro-sampling).

Transmission electron microscopy (TEM/STEM) samples have to be thin enough to be electron transparent and produce the required contrast. In the life sciences samples often have to be dried, embedded, cut thin or stained. In materials science they often have to be made thin and free from artefacts produced during thinning.