Tabletop Scanning Electron Microscopy: New Technology for identification of microscopic arthropods

Wednesday, November 13, 2013: 4:50 PM
Meeting Room 6 A (Austin Convention Center)
Gary R. Bauchan , Electron & Confocal Microscopy Unit, USDA, Agricultural Research Service, Beltsville, MD
Jenny Beard , Queensland Museum, South Brisban, Queensland, Australia
Ronald Ochoa , PSI, ARS, USDA, USDA-ARS-PSI, Systematic Entomology Laboratory, Beltsville, MD
Scanning electron microscopy (SEM) has been used for many years as an excellent tool for observing microscopic arthropods. However, the high cost, space requirements, and extensive preparation of the samples has reduced its wide scale application.  Electron microscopy companies have miniaturized the SEM with the development of a variable pressure table top version (tt-SEM). The production of is instrument  has greatly reduced the cost of purchasing an SEM, they can fit on a small table top; they are light weight (160lbs); and they require only a single small vacuum pump and a laptop computer.  The tt-SEM can produce high resolution, high magnification images (15x to 30,000x) very similar to a standard SEM. The advent of the variable pressure SEM eliminates the requirement for complex sample preparation and coating with a metal. Samples are simply attached to a stub, placed into the sample chamber, which is then evacuated and the electron beam turned on for imaging.  There are a reduced number of variables for the beam conditions, two beam strengths (5kV, 15kV), and backscatter electron analysis is available for low contrast biological specimens. There are only two settings for high and low vacuum to reduce charging conditions in the chamber.  The reduction in variables allows for a simplified software menu that includes auto focus, auto brightness/contrast and easy magnification manipulation. Simple one click computer menus allow for easy use and rapid digital image capturing, and thus sharing with colleagues.  This new technology allows for rapid, accurate identification of microscopic arthropods for taxonomic purposes and may be used at port of entry, extension and state departments.