Eliminating Lateral Forces During AFM Indentation

We have implemented a technique to eliminate the in-plane lateral tip motion for AFM experiments that involve a cantilever deflection change due to bending. Because of the geometry limitation, there is an undesired lateral tip position change associated with the bending of the cantilever. Previous approaches for solving this problem used X-piezo motion to compensate this tip lateral motion based on the distance change between the tip and sample, or the Z-piezo travel. This method partially works based on the assumption that the cantilever deflection change is always proportional to the Z-travel distance, which is not true in many cases. The key factor in our approach is to apply X-piezo motion based on the cantilever deflection change. This is a direct and accurate method that will also take into account of the probe sample interactions. We will demonstrate the application results of this method with nanoindentation on polymer samples, as well as imaging on heterogeneous materials. The various kinds of calibration methods will be also discussed. Research supported by NIST/ATP Award #70NANB4H3055.