Principles of AFM

Setup of a typical AFM as it used to investigate cells. The AFM tip is mounted on a soft cantilever spring. The deflection of the cantilever is detected by on optical lever using a laser beam. The cantilever can be positioned in all three dimensions to allow scanning and interrogation of the sample. In this case an inverted optical microscope to allow coarse positioning of the tip and additional investigation of the sample.

Besides topographic imaging (see gallery) the AFM can be used to measure and apply local forces. This typically envolves taken so called force curves, i.e. monitoring the cantilever deflection while the tip is brought into contact with the sample and withdrawn again. You may want to visit animated versions of force curves on stiff and soft samples, which is the basis for measuring local elastic properties.

Current projects include the mechanics of cell migration and cell division and the actiivty of single enzymes.