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Atomic Force Microscope (AFM)

What is Atomic Force Microscopy?

Atomic force microscopy (AFM) is a type of Scanning Probe Microscopy that can be operated in air or water. The basic principle of AFM is whereby a fine tip is scanned across the surface of the sample to measure surface morphology and properties to construct a 3D image of the surface.

AFM has the advantage that it produces quantitative, 3-D images and less intrusive surface measurements with resolution of a few microns to below 10 Angstroms can be obtained. With the added benefits of small sample size, the ease of sample preparation and the different possible modes are possible, such as contact and force, AFM enjoys the upper hand in modern characterisation techniques.

Uses of AFM

AFM has become an extremely useful tool in materials science applications. In addition to imaging surfaces with nanometre resolution, the AFM can also be used to determine surface roughness, probe local changes in friction, measure surface forces, and assess changes in local elasticity over a sample surface. Recently, much attention has been focused on the interpretation of AFM force curves for characterizing tip-sample interactions. Through appropriate analysis of force curves, a wealth of information can be obtained regarding the mechanical, chemical, and adhesive properties of the surface.

The capabilities of the atomic force microscope (AFM) allow for the direct evaluation of local microstructural and property changes in complex material systems. The operation of the AFM in force mode allows for a more quantitative characterization of polymer behaviour under mechanical loads. In this mode, the probe tip is first lowered into contact with the sample, then indented into the surface, and finally lifted off of the sample surface. Concurrently, a detection system measures the probe tip deflection. The plot of tip deflection versus piezo motion is called a force curve.

The characterization of different materials on a sub-micron scale is necessary to evaluate their performance in a wide variety of applications. It is known that the nanoscale properties that control various aspects of material performance can be different from bulk properties due to differences in local chemistry or microstructure. The imaging capabilities of the AFM allows for the direct evaluation of local microstructural and property changes in these complex material systems.

How does this help us?

The Materials Engineering Research Institute has a Digital Instruments AFM/STM. Our system consists of a Nanoscope IIIa and a system controller fitted to a Multimode TM scanhead. It is designed for atomic-scale resolution imaging of material surfaces. Materials of interest cover a full range from metals, insulators, ceramics, polymers, and biological samples.

The instrument can perform the full range of Scanning Probe Microscopic (SPM) techniques including Contact Mode (CM-AFM), Tapping Mode (TM-AFM), Phase Imaging, Lateral Force Microscopy (LFM), Magnetic Force Microscopy (MFM), Electric Force Microscope (EFM) and Nanoindenting/Scratching with a variety of scanner sizes under ambient conditions. It also allows measurement of current vs applied biased voltage.

Who to contact

For more information on the Atomic Force Microscope please contact Matthew Kitchen

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