Extreme Close-Up: Behind the Scenes with the Scanning Electron Microscope
Under 750x magnification, it’s not hard to see the crunch factor in one of Florida Tech’s favorite breakfast cereals, Cinnamon Toast Crunch. The university’s newest scanning electron microscope, housed in the Link Building, can create images of details much smaller than a standard light microscope and employs X-ray analysis to reveal the elements making up the sample.
How It Works
Simply put, a scanning electron microscope captures an image of a specimen by zapping it with a beam of electrons. The image is essentially a map of the electrons’ migration through the specimen.
However, electrons behave much like electricity, explains Kevin Johnson, associate professor of oceanography and environmental science and manager of the College of Engineering’s scanning electron microscope, so the specimen must be conductive to capture a quality image. With organic samples, like Cinnamon Toast Crunch, a moth wing or a piece of coral, which are inherently nonconductive, the image will be best if they are treated or coated in a conductive substance to be viewed in the microscope.
Gold sputter-coating is one traditional solution. A super-fine dusting of gold particles, barely distinguishable to the naked eye (we’re not talking a bedazzled specimen charm here), helps guide the electron beam across the surface of the specimen.
From start to finish, the entire process of preparing and viewing the specimen takes about 30 minutes.
The result is an intensely intricate rendering of the very essence of the specimen. The X-ray elemental analysis, another special feature of the microscope, identifies the most abundant elements, decoding a specimen’s composition. In an engineering application, the scanning electron microscope might reveal tiny cracks in a material, identifying a weak point or other variations between samples.
The College of Engineering’s scanning electron microscope joins the university’s suite of advanced microscopy equipment. L. Holly Sweat, doctoral candidate in oceanography, captured the images for this article, and Gayle Duncombe, microscopy center manager in biological sciences, assisted with the specimen sputter-coating.