Atomic Force Microscopy
Atomic Force Microscopy (AFM) · Also known as: AFM, scanning probe microscopy, nanoindentation microscopy
Atomic Force Microscopy (AFM) is a scanning probe technique that measures nanoscale surface topography and mechanical properties by monitoring interactions between a sharp cantilever tip and a sample surface. Invented by Gerd Binnig in 1986 as an extension of scanning tunneling microscopy, AFM requires neither electrical conductivity nor vacuum operation, making it applicable to virtually any material. It provides three-dimensional topographic maps with sub-nanometer vertical resolution and lateral resolution approaching nanometers, along with simultaneous measurements of mechanical, electrical, and chemical properties.
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When to use it
AFM is ideal for measuring surface roughness, mapping local stiffness, studying adhesion forces, and imaging biological or soft materials that are damaged by electron beams. Choose contact mode for high resolution on hard samples; tapping mode for delicate or sticky samples; non-contact for minimal disturbance. Pair with EDS or Raman spectroscopy for correlated chemical/mechanical analysis. Avoid for very soft materials prone to tip sinking or for high-speed large-area surveys (slower than optical microscopy).
Strengths & limitations
- Produces 3D topographic maps with sub-nanometer vertical and nanometer lateral resolution
- Works on any surface: conductors, insulators, organic, biological, vacuum-free
- Simultaneous measurement of topography and mechanical properties (stiffness, adhesion, friction)
- Non-destructive for hard samples; minimal sample preparation required
- Real-time visualization enables dynamic monitoring and interactive exploration
- Scanning is slow compared to optical microscopy (minutes to hours for large fields)
- Lateral resolution depends on tip sharpness; dull tips degrade image quality
- Soft or sticky samples can trap the tip, causing crashes or artifacts
- Height accuracy limited by drift, thermal expansion, and cantilever calibration uncertainty
- Data interpretation in force spectroscopy requires detailed understanding of tip-sample interactions
Frequently asked
What is the difference between contact and tapping mode AFM?
Contact mode keeps the tip in continuous contact with the surface under constant force, providing high resolution but risking tip deformation or sample damage. Tapping mode vibrates the cantilever at its resonance frequency, briefly touching the surface each cycle; this reduces lateral forces and damage. Tapping is gentler; contact is faster and higher-resolution.
How do I get better lateral resolution?
Lateral resolution depends on tip radius and measurement bandwidth. Sharper tips (~5 nm radius) and higher scanning speeds improve resolution. Using younger, uncontaminated tips and optimizing setpoint force also help. Fundamental limits approach ~1 nm under ideal conditions.
Why does my image drift or distort over time?
Thermal expansion of the scanner, sample, and cantilever causes drift. Temperature fluctuations of even 0.1 K introduce errors of 10-100 nm over hours. Minimize thermal gradients, allow equilibration time, and use closed-loop feedback or image registration to correct drift.
Can AFM measure properties inside the sample, not just surfaces?
Not directly. AFM probes the sample-tip interface. Nanoindentation AFM measures mechanical properties to depth ~1 micrometer via force curves, but internal structures require cross-sectioning or complementary techniques like ultrasonic AFM.
Sources
- Binnig, G., Quate, C. F., & Gerber, C. (1986). Atomic force microscope. Physical Review Letters, 56(9), 930-933. DOI: 10.1103/PhysRevLett.56.930 ↗
- Eaton, P., & West, P. (2005). Atomic Force Microscopy. Oxford University Press. link ↗
- Butt, H. J., Cappella, B., & Kappl, M. (2005). Force measurements with the atomic force microscope: Technique, interpretation and applications. Surface Science Reports, 59(1-6), 1-152. DOI: 10.1016/j.surfrep.2005.08.003 ↗
How to cite this page
ScholarGate. (2026, June 3). Atomic Force Microscopy (AFM). ScholarGate. https://scholargate.app/en/materials-science/atomic-force-microscopy
Which method?
Set this method beside its closest kin and read them side by side — the library lays the books on the table; the choice is yours.
- Energy-Dispersive X-ray SpectroscopyMaterials Science↔ compare
- NanoindentationMaterials Science↔ compare
- Selected Area Electron DiffractionMaterials Science↔ compare