Q-Control - Controlling the force interaction in AFM

In scanning force microscopy often dynamic modes are used, in which in contrast to static modes the micromechanical probe is interacting with the sample surface just temporary. Thereby in principle it is possible to reduce the forces exerted by the probing tip on the sample. The Q-Control module is a modification or hardware add-on to scanning force microscopes that comprises an additional feedback circuit. It allows to increase the effective quality factor of the dynamic system. As a results a further significant reduction of the interaction forces between the probe and the sample can be achieved.

Various applications show that many highly sensitive surface structures, in particular ultrathin organic layers or biological samples in liquids, can only be non-destructively imaged and characterized by using such an active feedback circuit. Furthermore, Q-Control often allows to improve the maximum achievable resolution in topographical measurements and to increase the overall sensitivity for magnetic or electrostatic fields.