Understanding Atomic Force Microscopy (AFM): Principles, Modes, Applications and Instrumentation

AFM

Atomic Force Microscopy (AFM) is a technique that provides images detailing the surface of materials at the nano and micro scale. This allows the surface features and properties to be investigated, which is growing importance within industry as many processes now handle nanosized materials.

Features which can be analysed include:

  • Morphology surface texture
  • Surface roughness
  • Surface Area
  • Surface Volume

Properties which can be analysed include:

  • Topography
  • Electrical
  • Magnetic
  • Chemical
  • Optical
  • Mechanical

AFM Technology

AFM technology uses these main components: The AFM Probe; Photodetector; piezoelectric scanner and AFM Tip, which is/on a flexible cantilever.

  • The AFM Tip moves over features on the sample, which are at different heights. These differences cause the AFM Tip and Cantilever to deflect.
  • The deflection is constantly tracked by a laser beam reflecting from the back of the cantilever into a photodetector.
  • Information from the photodetector allows a feedback loop to maintain near-constant AFM cantilever
  • The deflection is maintained by controlling the height of the cantilever, which is done by a piezoelectric ceramic scanner (which also controls lateral position).
  • On top of all of this the AFM Tip coordinates are continually tracked during the scan, which is what allows the 3D image to be produced.

AFM Modes

This technology has been developed to have different modes of operation, which have advantages in different environments and can be used to analysed surface properties of polymer, ceramics, composites, glass and biological samples.

  • Contact Mode: AFM Tip is scanned over the sample while in constant contact. This mode allows lateral forces to be detected and is often used by those less experienced in AFM; however, it does cause high levels of tip damage.
  • Tapping Mode: This is slightly more technical as it uses a piezoelectric actuator to oscillate the probe at resonance frequency. The feedback loop then maintains this resonance frequency and allows the tip to not be in constant contact with the sample.
  • NonContact Mode: This mode ensures the least tip damage by oscillating the cantilever at near resonance frequency at a smaller amplitude, several nanometres away to avoid sample contact.

ICSPI

ICSPI make a range of AFM instruments which can be used to investigate material roughness, thickness, particles and phases for samples such as polymers, composites, metals, minerals, ceramics and biological materials. 

nGauge Atomic Force Microscope 

The nGauge AFM is a desktop atomic force microscope capable of resolving features with sub-nanometer precision. Suitable for those with little experience with AFM due to its AFM-on-chip technology, automatic approach and one-click configuration, allowing for ease-of-use and data to be collected with 3 minutes of sample loading. 

Redux AFM

This instrument is very similar to the nGauge, as it is also a benchtop system which can collect 3D topography data with sub-nanometer precision. But it is more ideal for precise navigation and large samples, so for those with more experience with atomic force microscopy.

Nenovision

Nenovision’s LiteScope uses atomic force microscopy technology combined with SEM to create more effective workflows and extend the possibilities of correlative microscopy and in-situ analysis. This setup has an open-hardware design for easy customization; can provide 3D correlative imaging; eliminates need for repetitive tasks and can be used in the following applications: 

  • Material Science 
  • Nanostructures 
  • Semiconductors 
  • Life Science

Merrow Analytical

For more information on these instruments and the technology they have adapted with atomic force microscopy click here

If you have samples that need surface characterisation, contact us here to discuss how your application and samples may fit the contract testing with have available on the nGauge instrument.