Comparing AFM Tip Adhesion Models: DMT vs. JKR and the Impact of Transition Parameter Errors

The pull-off (adhesive) force of the tip of an atomic force microscope relies on the bluntness of the tip. The DMT (Derjaguin, Muller, and Toporov) and model JKR (Johnson, Kendall, and Roberts) model are used to estimate this adhesive force. Which to use depends on the Tabor transition parameter. However, the process of determining this parameter has its caveats. Hence, this paper investigates the difference between estimating the pull-off force using the two models for non-integer values of tip bluntness. It was found that the sharper the tip the more it is sensitive to the pull-off force. Moreover, the difference between the two models becomes more pronounces the more spherical it is.