Scanning electron microscopy (SEM) is invented in 1965 compared to modern cell biology research tools, mainly is the secondary electron signal imaging to observe the surface morphology of the samples, with a very narrow electron beam to scan the samples by electron beam and the sample interactions produce various effects, which is mainly secondary electron emitted from the sample.

The two electron can generate the image of the sample surface, which is set up according to the time sequence when the sample is scanned.