Dynamic force microscopy simulator (dForce): A tool for planning and understanding tapping and bimodal AFM experiments

Abstract

We present a simulation environment, dForce, which can be used for a better understanding of dynamic force microscopy experiments. The simulator presents the cantilever-tip dynamics for two dynamic AFM methods, tapping mode AFM and bimodal AFM. It can be applied for a wide variety of experimental situations in air or liquid. The code provides all the variables and parameters relevant in those modes, for example, the instantaneous deflection and tip-surface force, velocity, virial, dissipated energy, sample deformation and peak force as a function of time or distance. The simulator includes a variety of interactions and contact mechanics models to describe AFM experiments including: van der Waals, Hertz, DMT, JKR, bottom effect cone correction, linear viscoelastic forces or the standard linear solid viscoelastic model. We have compared two numerical integration methods to select the one that offers optimal accuracy and speed. The graphical user interface has been designed to facilitate the navigation of nonexperts in simulations. Finally, the accuracy of dForce has been tested against numerical simulations performed during the last 18 years.

High-Speed Nanomechanical Mapping of the Early Stages of Collagen Growth by Bimodal Force Microscopy

“…1 was validated by numerical simulations provided by an opensource code. 41 Eq. 2 described the loss tangent associated with the 1st mode.…”

Nanomechanical mapping of soft materials with the atomic force microscope: methods, theory and applications

“…55,56 Computational solutions enable to explore the dynamic behaviour of complex models. This task is helped by the existence of two numerical codes dForce 57 and VEDA 58 that enable to simulate the response of a dynamic AFM for a variety of sample models. Numerical simulations have been applied to determine the force based on a SLS response and to compare it with experiments performed with an amplitude modulation AFM on elastomers and polycarbonate samples.…”

Identification of HIV-1–Based Virus-like Particles by Multifrequency Atomic Force Microscopy

“…Comparison with the TEM image can be used to assign a brighter area of the F 2 image with a softer surface associated with the VLP membrane, while the darker area should correspond to a hardening of the surface induced by the nuclear protein capsid embedded in the VLP. In this sense, bimodal AFM arises as a powerful tool to investigate complex biological material due to its capability of distinguishing among mechanically different structures of the biological units, with wide applicability in the biophysics community (26).…”