Atomic Force Microscopy: The Eyes of Nanotechnology

Atomic force microscopy (AFM) is the principal technology that scientists and researchers use to view and manipulate samples at the nanometer scale, which is why it’s called the “eyes of nanotechnology.” The atomic force microscope is a high-resolution imaging and measurement tool that allows researchers to directly view single atoms or molecules that are only a few nanometers in size, then produce a three-dimensional map of the sample’s surface.

The number of applications for AFM has exploded since the technology was invented in 1986 and now spans many areas of nanoscience and nanotechnology. AFM provides the ability to view and understand events as they occur at the molecular level. This will increase knowledge of how systems work and lead to advancements in such areas as drug discovery, life science, materials science, electrochemistry, polymer science, biophysics and biotechnology.

A number of advantages over other technologies make AFM a favorite with researchers. The chief difference between AFM and other microscopy techniques is the measure of resolution. While electron and optical microscopes provide a standard two-dimensional horizontal view of a sample’s surface, AFM also provides a vertical view. The resulting images show the topography of a sample’s surface. And while electron microscopes work in a vacuum, most AFM modes work in ambient or liquid environments. AFM does not require any special sample preparation that could damage the sample or prevent its reuse.

How AFM works

AFM is part of a family of instruments called scanning probe microscopes (SPM). AFM uses a probe moving across the sample’s surface to identify its features. The probe is a sharp tip, usually made of silicon, at the end of a cantilever that bends in response to the force between the tip and the sample being viewed. That deflection is measured and the AFM records the surface topography. The tip never touches the sample surface, thus preventing damage to the sample.

The predecessor of AFM is scanning tunneling microscopy (STM), or the scanning tunneling microscope. Gerd Binnig and Heinrich Rohrer invented STM in 1981 and shared the 1986 Nobel Prize in physics for their innovation. AFM has surpassed STM by providing broader potential and applications because it can be used for imaging any conducting or non-conducting surface. STM is limited to imaging conducting surfaces.

Text and images provided by Agilent Technologies. On Nov. 29, 2005 Agilent Technologies aquired Molecular Imaging Corp. a premier developer and supplier of AFM systems for high-resolution imaging in fluids or ambient air under controlled temperature and environmental conditions.