SCANNING ELECTRON MICROSCOPY: PRINCIPLES AND APPLICATIONS IN THE FIELD OF BIOSCIENCES

M. CLAUDIA MARCHI

La Plata

Workshop; Imaging Techniques for Biotechnology and Biomedical Applications; 2016

CONICET

      This presentation summarizes the basic principles of scanning electron microscopy and the capabilities of the technique with different examples of applications in Biology and Nanotechnology.       The scanning electron microscope (SEM) uses electrons to form an image. A beam of electrons is produced at the top of the microscope (electron gun) and follows a vertical path through the column of the microscope, it makes its way through electromagnetic lenses which focus and direct the beam down towards the sample.The beam passes through pairs of scanning coils or pairs of deflector plates in the electron column, typically in the final lens, which deflect the beam in thex and y axes so that it scans over a rectangular area of the sample surface. Different detectors collect the signals, and convert them into other signals that are sent to producing an image. The signals result from interactions of the electron beam with the atoms at or near the surface of the sample. This image is then digitally captured and displayed in a computer monitor. Magnification in a SEM can be controlled over a range of about 100 to 1,000,000 times or more. The type of signals produced by our SEM include secondary electrons, back-scattered electrons (BSE), energy dispersive spectroscopy (EDS), Electron back-scattered diffraction (EBSD) and electron beam lithography (EBL).