The scanning electron microscope is used to image the surface of a conducting sample by scanning it with a high energy beam of electrons. Some SEMs have additional software enhancements than enable them to focus the beam on a photomask for E-beam lithography or are equipped for focused ion beam (FIB) milling.
Microfluidics and nanofluidics have lots of applications that require SEM. This post contains a good collection of videos explaining basics of SEM and how to use the instrument.
There are total of six videos.