Characterization of dimensions of ellipsoidal microparticles via electron microscopy

SUMMARY The analysis and the use of metallic shadow casting and specimen tilting for accurately determining the dimensions of microellipsoids by electron microscopy (EM) are presented. The procedure uses the direct image and two different shadows or two different specimen tilts to unambiguously determine the dimensions of an ellipsoid. A novel computer‐aided matching procedure is used to determine dimensions and orientations. The analysis was applied to a sample of polymer prolate microspheroids, which have recently been synthesized in our laboratory. The shape of the particles was confirmed and their dimensions and orientations were determined. The particles were shown to have a length (twice the principal axis) of 3.30±0.02 μm and a diameter (twice the minor axis) of 1.66±0.04 μm. Thus, both EM techniques were demonstrated to be practical and precise for determining dimensions of individual microellipsoids.