AFM lab
Soft Matter at Interfaces

Our AFM laboratory specialises both on force measurements and scanning in air and liquid medium. Hence, we operate several dedicated microscopes with individual features in scanning speed, resolution characteristics and available sample environment cells. The microscope suite includes two Asylum Research MFP3Ds (one with a coupled fluorescence microscope), an Asylum Research Cypher and a JPK NanoWizard II.

Atomic Force Microscope (AFM) is a type of scanning probe microscopy measuring distance dependent interaction forces (10-4 down to 10-12 N) between surfaces with high spatial resolution (down to 10-9 m) [1]. The technique can be used in vacuum, gaseous or liquid environments and at various temperatures. Combining its relative simple design, resolution and versatility promotes this technique to one of the most widely used to quantitatively measure the interactions between surfaces and to investigate surface topologies.

The central unit of an AFM is a flexible cantilever with a probe at its end. In the scanning probe AFM, the probe is a sharp tip with a radius of curvature around 5 – 50 nm. Force measurements are mostly performed with a micron scale spherical colloidal probe attached on the cantilever [2]. The flexible cantilever is bent depending on the interactions between the probe and the surface. The principle of the AFM exactly lies behind monitoring this bending. It is done by collecting the deflection of a laser beam reflected from the top of the cantilever.

[1] Butt, H.; Cappella, B. & Kappl, M. Surf. Sci. Rep. 2005, 59, 1-152

[2] Ducker, W.; Senden, T. & Pashley, R. Nature 1991, 353, 239-241

Lab impressions