Developments in dynamic atomic force microscopy techniques to characterize viscoelastic behaviors of food materials at the nanometer-scale

The atomic force microscope measures topographical and mechanical properties of surface-deposited materials by characterizing the forces exerted on a cantilever probe and choosing a mechanical model that appropriately transforms this to viscoelastic data. In dynamic modes, the cantilever oscillates at driven frequencies, and this oscillatory motion is dampened by viscoelastic forces exerted by the sample. Recent developments in dynamic modes are discussed, including techniques to limit noise, control the time and depth of sample indentation, modulate frequency and amplitude to quickly identify peak forces and resonances, improve accuracy in liquids, and reliably excite the cantilever and sample at multiple frequencies, all of which improve speed, accuracy, and resolution of imaging and viscoelasticity determination in food materials.