Torsional Sensitivity and Resonant Frequency of an AFM With Parallel Sidewall Probes

Abstract

The resonant frequencies and torsional sensitivities of an atomic force microscope (AFM) assembled cantilever probe which comprises a horizontal cantilever, two vertical extensions and two tips located at their free ends are studied. This probe makes the AFM capable of measuring, for instance, the outer/inner diameter, roundness and roughness of microstructures like micro-holes and micro nozzles which leads to a time-saving swift scanning process. In this work, the effects of the sample surface contact stiffness and the geometrical parameters such as the ratio of the vertical extension length to the horizontal cantilever length and the distance of the first vertical extension from the clamped end of the horizontal cantilever on torsional resonant frequencies and sensitivities are assessed. These geometrical effects are illustrated in some figures. The results show that the low-order vibration modes are more sensitive for low values of the contact stiffness but this situation is not valid for high values.