The role of field-emission SEM in biology in the 21st century

Abstract

To predict how field emission SEM (FESEM) will be applied to biological investigation in the transition to the 21st century requires some recapitulation of how dramatically changes have occurred in the last half of the 20th century. Although, initially developed in the 1930s by Knoll and later, von Ardenne, the commercial production of instruments in the 1960s was brought about chiefly due to contributions in secondary (SE) and backscatter (BS) electron detector design from the Cambridge group led by Oatley. Continued instrumentation development over the next three decades led to numerous improvements, i.e. new lanthanum hexaboride emitters, advances in specimen preparation, and was culminated in the late 1980s, by the commercial development of a high resolution SEM possessing short focal length lenses together with a cold field emission electron gun, resulting in electron probes with diameters of 3nm at 1.5 keV and 0.5nm at 30 keV.From the perspective of a biologist using FESEM for both structural and immunocytochemical studies, I would like to suggest changes in both instrumentation and methodology that would be of great practical value today, and would hopefully be surpassed by standard features in new instruments available at the turn of the century.