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An Atomic Force Microscope (AFM) investigates atomic-scale topography by scanning a probe with an extremely fine tip over the surface of a sample.
An AFM is founded on the atomic-scale interactions between the extremely sharp tip of a probe and surface. There are several techniques and approaches to using an AFM. In particular, modifying the probe tip allows an AFM to investigate a wide range of surface qualities, like adhesion forces and viscoelastic qualities.
An AFM can evaluate many different types of specimens, including polymers, thin films, and fine powders. Over the years, the technique has also become a go-to way to acquire nano-scale details and biomechanical qualities of biological specimens.
The principle of an AFM is founded on the detection of interactions between the sample surface and probe tip. These interactions are passed to a highly-responsive cantilever, the motion of which is measured to gather information.
There are multiple approaches to measuring cantilever motion. Most AFMs use a laser-based optical system. This involves laser light being reflected off a moving cantilever and into an optical detector. As the probe is passed over the sample surface, very small forces are generated, and these forces deflect the cantilever. The deflection of the cantilever is known as “stiffness of cantilever” and can be visualized in real-time on a computer display.
Because of its precision and ability to gather many different kinds of information, an AFM is extremely important in a number of different scientific fields.
Microbiology and Genetics
AFMs are commonly used to evaluate the mechanical properties of cells, including cell stiffness and viscoelasticity. They can also be used to study the exterior of living cells down to the molecular interactions. AFM-based spectroscopy analysis is often used to evaluate cell adhesion rheological qualities. In genetics, an AFM can be used to recognize mRNA in single living cells.
Probably the most critical benefit of an AFM in biology is the ability to investigate biological specimens in their natural environment. In particular, it can investigate both in vitro and in situ in buffer solutions, and in vivo without any preparation. There are no limitations to the kind of medium used for investigations, including aqueous, non-aqueous, any temperature and any chemical composition.
Medicine and Pharmacology
An AFM also allows for a novel process to determine the qualities of biological membranes, which are currently a major focus of many biological studies. The capacity of an AFM to have a look at the interaction between a cell membrane and drug is a very valuable benefit of an AFM in pharmacological studies. Looking at membrane proteins at the molecular level with an AFM has established a whole new area of study. The resulting development of biofilms has had far-reaching impacts in medicine and dentistry.
Investigation of microbial surfaces with an AFM has also had a major impact. Even though microbial surfaces were the focus of significant study, researchers have more recently been interested in the quantitative examination of the molecular interactions at these surfaces. In addition to creating high-resolution imaging of microbe exteriors, AFM also offers a way to measure molecular forces and physical qualities located at the microbial exterior of interest.
Cutting-edge materials science is currently based on studying and examining materials at the atomic level, and the AFM has facilitated many advances in the field. The investigative tool has been used to analyze the thickness of thin films, make incredibly fine determinations of surface roughness, determine the sizes of various particles, see grain size distribution and image polymer surfaces at the atomic scale in three dimensions.
Sources and Further Reading