Extraction algorithm for longitudinal and transverse mechanical information of AFM.

The atomic force microscope (AFM) can measure nanoscale morphology and mechanical properties and has a wide range of applications. The traditional method for measuring the mechanical properties of a sample does so for the longitudinal and transverse properties separately, ignoring the coupling between them. In this paper, a data processing and multidimensional mechanical information extraction algorithm for the composite mode of peak force tapping and torsional resonance is proposed. On the basis of a tip–sample interaction model for the AFM, longitudinal peak force data are used to decouple amplitude and phase data of transverse torsional resonance, accurately identify the tip–sample longitudinal contact force in each peak force cycle, and synchronously obtain the corresponding characteristic images of the transverse amplitude and phase. Experimental results show that the measured longitudinal mechanical characteristics are consistent with the transverse amplitude and phase characteristics, which verifies the effectiveness of the method. Thus, a new method is provided for the measurement of multidimensional mechanical characteristics using the AFM. HIGHLIGHTS: • Based on a composite method of peak force tapping and torsional resonance, a multidimensional mechanical signal measurement system for an atomic force microscope (AFM) is constructed that overcomes the inability of the peak force tapping mode to measure the transverse mechanical properties of a sample and the inability of the traditional torsional resonance mode to realize closed-loop feedback control of stable morphology. It can thus obtain both longitudinal and transverse mechanical information of a sample simultaneously. • Based on a model of the interaction between the AFM tip and a sample, longitudinal peak force data is used to synchronize and decouple transverse torsional resonance amplitude and phase data, enabling accurate identification of the longitudinal contact force between tip and sample in each peak force cycle, as well as synchronous acquisition of the corresponding characteristic images of transverse amplitude and phase. • The improved contact point registration algorithm accurately identifies the signal boundary for each peak force cycle, providing a better way of dealing with background noise and obtaining more accurate image data. [ABSTRACT FROM AUTHOR]