What is Atomic Force Microscopy?
Atomic force microscopy (AFM) is a scanning probe technique that images and measures surface properties at the nanometer scale by detecting forces between a sharp tip and the sample surface. AFM can resolve features down to the atomic scale and, unlike electron microscopy, operates in air, liquid and controlled gas environments without requiring conductive samples or vacuum conditions.
How Does AFM Work?
A microfabricated cantilever with a sharp tip at its end is scanned across the sample surface. As the tip interacts with the surface, forces cause the cantilever to deflect. A laser beam reflected from the back of the cantilever onto a position-sensitive detector measures these deflections with sub-nanometer precision. A feedback loop maintains constant force or amplitude, and the feedback signal is used to reconstruct a three-dimensional topography map of the surface.
AFM Imaging Modes
- Contact mode — tip remains in continuous contact with the surface; suitable for hard materials
- Dynamic (tapping) mode — cantilever oscillates near its resonance; minimal force on soft samples
- Non-contact mode — tip senses long-range forces without touching the surface
- PeakForce QNM — simultaneous topography and nanomechanical property mapping
- Kelvin Probe Force Microscopy (KPFM) — maps surface potential and work function
- Magnetic Force Microscopy (MFM) — images magnetic domain structures
- Conductive AFM (cAFM) — maps local electrical conductivity
What Properties Can AFM Measure?
- Surface topography with sub-nanometer vertical resolution
- Nanomechanical properties: Young’s modulus, adhesion, stiffness, dissipation
- Surface potential and charge distribution
- Magnetic domain structure
- Piezoelectric response (PFM)
- Local electrical conductivity and current-voltage characteristics
AFM vs. Electron Microscopy
AFM and SEM/TEM are complementary techniques. AFM provides true three-dimensional surface topography and quantitative property maps in ambient conditions with no special sample preparation. Electron microscopy delivers higher lateral resolution and can provide elemental composition data but requires vacuum conditions and often conductive coatings for non-conductive samples. Many research laboratories use both techniques.
Choosing the Right AFM
Key factors in AFM selection include scan range, noise floor, supported imaging modes, operating environments (air, liquid, temperature control) and software capabilities. Entry-level systems such as the NanoSurf EasyScan 2 offer guided operation for teaching and routine analysis, while advanced research platforms like the DriveAFM provide the lowest noise performance and the broadest mode selection for demanding research.
AFM Applications by Industry
- Materials science — polymer morphology, fiber surface roughness, coating uniformity
- Semiconductors — wafer roughness, thin film grain structure, device surface analysis
- Biology and life sciences — cell membrane imaging, protein assembly, DNA visualization
- Electrochemistry — in-situ electrode surface changes during cycling
- Pharmaceuticals — crystal habit analysis, API surface characterization
NewRoad distributes NanoSurf AFM systems across the full range from compact educational instruments to high-performance research AFMs. Contact us to find the right solution for your application.
