Atomic Force Microscopy Sensing Using Multiple Modes

An atomic force microscope (AFM) explores the topography of a sample surface using a micro-sized flexible cantilever, which works as a flexible robot arm. The flexible cantilever is controlled to keep vibrating when an AFM works in the tapping mode. The cantilever is modeled as a flexible beam instead of a point mass system in this paper. The nonlinear interaction force between the tip and sample surface is also modeled. A simulation environment is developed to analyze the dynamics of cantilevers using the flexible beam model. Simulation results confirm that the flexible beam model can represent the system more accurately than the point-mass model. It has been shown that lower modes are more sensitive to changes of surface topography or surface materials when the cantilever is driven to vibrate at a higher harmonic mode. At the same time, this simulation environment also provides a more accurate way to validate the design of a new AFM probe and AFM controller than simulation packages which use the point-mass model