Atomic Force Microscopy (AFM) is a technique that allows to visualize with a nanometric resolution the three-dimensional morphology of the surface of a material, and to map some of its properties (adhesive, mechanical, magnetic, electrical, ...). This technique allows the observation of the surfaces of all types of solid materials (polymers, powders, glasses, textiles, fibers, biological samples, nanoparticles...) in air and in liquid medium at atmospheric pressure.
The principle of AFM is based on the measurement of the different interaction forces (ionic repulsion forces, Van-der-Waals forces, electrostatic forces, etc...) between the atoms of the surface of the sample to be observed and the atoms of a nanometric probe tip, fixed under a flexible microlever. A laser beam, reflected on the back side of the microlevier and directed on a 4 quadrants photodiode. The tip scans the surface and follows the topography of the sample, giving a three-dimensional image of the analyzed material. This image allows in particular to calculate the roughness parameters.
Simultaneous measurement of 3D topography and mechanical parameters The force applied on the tip is controlled to preserve the sample and the AFM point. The approach-shrinkage curves at 2 kHz are obtained (force spectroscopy) and analyzed in real time in order to extract the mechanical parameters (Young's modulus, tip-surface adhesion, deformation...). After calibration of the tip, the measurements become quantitative.