Modeling and Analysis of Auto-Tapping AFM

The paper presents a new Atomic Force Microscopy setup where the cantilever gets excited by a positive feedback loop containing a saturation function. The proposed scheme can be easily modeled and analyzed in the frequency domain using harmonic balance techniques. In imaging applications, we show that an additional controller for the saturation threshold can further reduce the topography error. Preliminary results in experiments confirm the effectiveness of this operating mode, providing good topography resolution and removing some of the known drawbacks of standard dynamic setups.