Electron microscopy offers numerous advantages to researchers working on the micro- and nanoscale. All of these benefits can be used for applications involving the analysis of particles, and vendors have developed particular software packages for these analyses.

For particle analysis, SEM is the most common form of electron microscopy used, and it is generally coupled with one or more energy dispersive x-ray spectrometers (EDS), which provide information about elemental composition. Automated image analysis software can identify individual particles within the scanned sample area and calculate particle parameters, including size, shape, length (for fibers) and elemental composition.

There are many distinct application areas for this analysis. Airborne particles captured by filters can be analyzed to quantify air quality. For environmental samples, analysis can provide information on the density and composition of particulate matter. For instance, while inhaled fine particles are generally considered to have adverse health effects, this negative effect is likely worse for particles containing mercury. The technique can also be used to analyze indoor air samples, although the additional analytical power is generally only justified for sensitive manufacturing processes, where a source of contamination needs to be identified.

Particles can also be recovered from oil filters, and SEM particle analysis can help to identify sources of wear metals in engine oils. This analysis is common in government and military applications, as well as in R&D in the aerospace and automotive industries.

Another interesting application is in forensics, for the analysis of gunshot residue. The method can be used to not only verify the presence of gunshot residue, but also potentially identify the type and source of ammunition. This application is specific enough that there are dedicated solutions.

While it perhaps strains the meaning of particle, these methods can also be used more generally for “feature” analysis. Common examples include the analysis of inclusions in steel or other manufactured metals, or mineralogical identification of individual grains in geological samples. The same image analysis algorithms that can detect individual particles can also function to identify these different features or particles locked into a solid matrix.

Since these particle analysis methods commonly require the contribution of the information from the EDS detector, the software solutions for particle analysis by SEM are often provided by the EDS analyzer vendor, rather than the electron microscopy vendor. Hence, the leaders in this area are the EDS vendors Oxford Instruments and Bruker, neither of which provides SEMs. Stemming from its acquisition of Aspex (see IBO 1/15/12), FEI is fairly unique in the market for offering dedicated SEM systems for these applications. Most of the other major SEM and EDS vendors also compete with their own solutions.

Electron Microscope Particle Analysis at a Glance:

Leading Suppliers

• Oxford Instruments

• Bruker

• FEI

Largest Markets

• Government

• Aerospace/Automotive

• Metals

Software Cost

• NA