What is a common limitation of Scanning Electron Microscopy?

Scanning Electron Microscopy (SEM) is indeed characterized by its requirement for a vacuum during operation. This is crucial because the electrons used to create images must travel freely without interference from air molecules. The vacuum allows the electrons to maintain their energy and prevents scattering, which would degrade the quality of the images produced. By utilizing a vacuum, SEM can achieve high-resolution imaging, allowing for detailed examination of surface structures at the nanoscale.

While other limitations exist for SEM, such as the inability to analyze certain kinds of samples without preparation (which is not necessarily related to their biological nature), the need for a vacuum is fundamental to its operational principle. Additionally, while SEM typically generates two-dimensional images and has a limited depth of field, these factors do not fundamentally relate to the operational requirements like the vacuum does. The necessity of a vacuum highlights a key aspect of SEM that differentiates it from other imaging techniques, making it an essential consideration in its application.