Feedback scheme for improved lateral force measurement in atomic force microscopy

This paper proposes a signal based on a feedback scheme that gives a measure of lateral forces in atomic force microscopy. This measure, unlike the typically used lateral deflection signal, is not corrupted by the geometrical crosstalk between the normal and lateral signals, accounts for inertial forces experienced by the cantilevers during scans, and misinterpretations due to irregular sliding. This measure varies linearly with the lateral forces for a larger range of forces and scanning bandwidth than the lateral deflection signal. The sensing bandwidth depends on the control design for the feedback scheme. We also present the design of an actuator that enables the lateral feedback scheme. Experimental results are presented that show the inaccuracies in the lateral deflection method for lateral measurement and how these are addressed by the feedback scheme.