Atomic force microscopy

Atomic force microscopy (pronunciation: a-tom-ic force mi-cros-co-py, from the Greek atomos meaning indivisible, force from the Latin fortis meaning strong, and microscopy from the Greek mikros meaning small and skopein meaning to look or see) is a high-resolution imaging technique that allows for the visualization of surfaces at the nanoscale.

Overview

Atomic force microscopy (AFM) is a type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit. The information is gathered by "feeling" or "touching" the surface with a mechanical probe. Piezoelectric elements that facilitate tiny but accurate and precise movements on (electronic) command enable precise scanning.

History

The AFM was invented by Gerd Binnig, Calvin Quate, and Christoph Gerber in 1986, and is part of a larger family of scanning probe microscopes. The first commercially available atomic force microscope was introduced in 1989.

Operation

The AFM consists of a cantilever with a sharp tip (probe) at its end that is used to scan the specimen surface. The cantilever is typically silicon or silicon nitride with a tip radius of curvature on the order of nanometers. When the tip is brought into proximity of a sample surface, forces between the tip and the sample lead to a deflection of the cantilever according to Hooke's law. Depending on the situation, forces that are measured in AFM include mechanical contact force, van der Waals forces, capillary forces, chemical bonding, electrostatic forces, magnetic forces (in Magnetic Force Microscopy), etc.

Applications

AFM can be used in various modes, depending on the particular application. These include contact mode, non-contact mode, and tapping mode, among others. AFM has many uses in various fields such as solid-state physics, semiconductor science and technology, molecular engineering, polymer chemistry and physics, surface chemistry, cell biology, and medicine.

Related Terms

External links

Medical encyclopedia article on Atomic force microscopy
Wikipedia's article - Atomic force microscopy

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