Atomic force microscope. Television screen (left) displaying a specimen being analysed by an atomic force microscope (AFM, right). AFMs are tools for studying the surfaces of objects at an atomic level. They work by holding an extremely fine stylus" (usually a diamond crystal) in contact with the sample, and slowly moving it across its surface. The stylus is spring-loaded, and its deflection is detected and can be converted into a computer map of the surface. The AFM is similar in principle to the scanning tunnelling microscope (STM), but has the advantage that the subjects to be studied do not have to conduct electricity."