Akademik Veri Yönetim Sistemi
The 16th International Conference on Vibration Problems (ICOVP-2025) & 11th International Conference on Wave Mechanics and Vibrations (WMVC-2025), Lisbon, Portekiz, 2 - 05 Eylül 2025, ss.1-7, (Tam Metin Bildiri)
Multi-frequency AFM techniques bring great opportunities for obtaining surface topography and extracting material properties simultaneously. Scanning a micro-cantilever over a sample surface, tip-sample interaction forces nonlinearly affect the oscillation observables, used to quantify the micro-cantilever sensitivity. In the current study, single-, trimodal-, and hexamodal-frequency excitation schemes are applied to explore micro-cantilever responses to Van der Waals forces at separation distances below 20 nm. A multi-mode lumped parameter model is utilized to determine oscillatory motions of four commercial AFM micro-cantilevers with different mechanical features under Van der Waals forces. The simulation results indicate that observables can simply be used to quantify the sensitivity to Van der Waals forces within the separation distance range of 3 - 15 nm. For instance, the amplitude at the sixth flexural eigenmode exhibits more fluctuations (within the range of 5 - 30 pm) for the lowest elastic stiffness (k16=6488.7 N/m) in the hexamodal-frequency operation, when compared with the single-frequency excitations. Moreover, in the hexamodal-frequency excitations, the highest range of phase shift at the fifth flexural eigenmode (around the range of 39° - 156°) is also noted within the separation distance range of 3 - 13 nm for the AFM micro-cantilever, which is made of silicon material, rather than cellulose nanofiber and silicon nitride materials. As expected, the fundamental and higher flexural eigenmodes exhibit notable responses to varying quality factors and tip radii. Therefore, based on the theoretical results, the mechanical features of the micro-cantilevers and the properties of working mediums can be optimized for enhanced sensitivity to Van der Waals forces.