STMs can observe how atoms are arranged, but because they utilize tunnel current they cannot be used to observe non-conductors. To address this shortcoming, Gerd Binnig of IBM's Zurich laboratory, and Stanford University physicist Calvin Quate, invented the atomic force microscope (AFM), a type of SPM that makes use of the special "atomic forces of attraction and repulsion arising between atoms.

When two objects approach each other beyond a certain distance, forces of attraction between atoms are generated, becoming stronger the closer the objects are brought, but forces of repulsion are also generated once they make contact. AFMs work by using a probe as one of those objects, measuring the movements of the probe as it is affected by the atomic forces arising between it and the specimen being observed to generate an image of the specimen.

Since atomic forces exist universally, AFMs can be used to observe the surfaces of all kinds of substances.

· How Atomic Force Microscopes ( AFMs) Work