Characterising visco-elastic response
A viscoelastic surface has a characteristic delay time between applied load and material response. When this delay time becomes longer than the period of cantilever oscillation, the force quadrature curves become hysteretic. Using a moving surface model one can extract the characteristic time constants for tip penetration in to the surface, and relaxation of the free surface.
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Machine learning to map mechanical response
Intermodulation AFM gives some 60 amplitude and phase images, in one scan at normal speed (2 min. for 256 x 256 pixels). Each pixel represents a single point in a abstract 60-dimensional 'feature' space. Machine learning attempts to group or cluster the pixels in this space. The ImAFM Software Suite comes with functionality for k-means clustering. Other clustering algorithms are easily programmed using the scripting interface and the Python module scikit-learn.
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