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In this work, amplitude modulation atomic force microscopy (AM-AFM) based on the higher flexural modes of the microcantilever is investigated by a numerical approach. The amplitude-distance and phase-distance curves for the first four flexural modes are obtained and compared. The dependence of phase on elastic modulus and viscosity of the sample is analyzed. Results show that a higher flexural mode yields a larger amplitude and phase in the repulsive regime and reduces the bistability, but causes a larger sample deformation and peak repulsive force. Compared to that of a lower flexural mode, the phase of a higher flexural mode provides higher sensitivity to viscosity variation for relatively large moduli. [ABSTRACT FROM AUTHOR]

A theoretical model for calculating the Young’s modulus of multi-layer microcantilevers with a coating is proposed, and validated by a three-dimensional (3D) finite element (FE) model using ANSYS parametric design language (APDL) and atomic force microscopy (AFM) characterization. Compared with typical theoretical models (Rayleigh-Ritz model, Euler-Bernoulli (E-B) beam model and spring mass model), the proposed theoretical model can obtain Young’s modulus of multilayer microcantilevers more precisely. Also, the influences of coating’s geometric dimensions on Young’s modulus and resonant frequency of microcantilevers are discussed. The thickness of coating has a great influence on Young’s modulus and resonant frequency of multi-layer microcantilevers, and the coating should be considered to calculate Young’s modulus more precisely, especially when fairly thicker coating is employed. [ABSTRACT FROM AUTHOR]