Dynamics of contact-mode atomic force microscopes

The rapid development of the atomic force microscope (AFM) has been motivated by a continuous unfolding of new applications and fundamental research areas utilizing AFM technology. As a result, there is a demand for better understanding of its dynamics and control to cope up with application requirements. This work presents a dynamic model for an AFM including its scanner, cantilever, probe-sample interaction force, and a simple sliding friction model. A description of possible sources of disturbances and noises are also given. Using a PI controller, simulations for constant-speed contact-mode scanning are presented. Simulation results were capable of reproducing experimental observations which are also presented. The results demonstrate the high sensitivity of AFM images to scan parameters and illustrate some potential artifacts that can result if parameters are not properly selected