Atomic Force Microscopy (AFM) is a surface characterization tool that can provide topographic images and quantitative information in both lateral and vertical dimensions. In addition to topgraphical information, AFM can provide mechanical properties information, including elastic modulus and adhesion.
How AFM works – A topographical image is generated when a cantilever with a sharp tip is scanned across the sample surface and the deflection or amplitude of a laser beam reflected from the back of the cantilever is monitored.
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Instrumentation Available
Key Attributes
- High resolution imaging: lateral resolution 1 nm (depending on tip), vertical resolution 0.1 nm
- Samples can be imaged in both air and fluid environments
Strengths
- Samples do not need to be coated or placed in vacuum
- High spatial resolution
- Quantitative measurements in x, y and z
- Allows imaging of biological in real time and in physiological conditions
Limitations
- Scan range limits: 100µm laterally (xy) and 5µm vertically (z) for the Multimode and 150µm laterally (xy) and 20µm vertically (z) for the Catalyst
- Sample must fit on sample stage. For the multimode, the sample must be 1 cm x 1 cm square or smaller.
- Imaging can cause damage to soft samples
Applications
- Assessing the surface roughness of thin films before and after processing
- Measuring the adhesion between the tip and sample surface
- Measuring step heights
- Measuring or mapping the mechanical properties of biological materials such as cells or tissues
- Visualizing changes to a sample (i.e. crystal growth) in real time
Additional Reading
