Focused ion beam scanning electron microscopy in biology

Since the end of the last millennium, the focused ion beam scanning electron microscopy (FIB‐SEM) has progressively found use in biological research. This instrument is a scanning electron microscope (SEM) with an attached gallium ion column and the 2 beams, electrons and ions (FIB) are focused on one coincident point. The main application is the acquisition of three‐dimensional data, FIB‐SEM tomography. With the ion beam, some nanometres of the surface are removed and the remaining block‐face is imaged with the electron beam in a repetitive manner. The instrument can also be used to cut open biological structures to get access to internal structures or to prepare thin lamella for imaging by (cryo‐) transmission electron microscopy. Here, we will present an overview of the development of FIB‐SEM and discuss a few points about sample preparation and imaging.