Development of rough viscoelastic contact theories and manipulation by AFM for biological particles: any geometry for particle and asperities

Researchers are interested in simulating the manipulation of biological micro/nanoparticles by the atomic force microscope. However, there are many obstacles practically, and there are still numerous unknowns and uncertainties regarding the interactions in bio-environments between biological micro/nanoparticles with different geometries. Most of the previous works performed on the manipulation of biological particles have been conducted on various particles with presumed spherical, and sometimes cylindrical, shapes. But, as we know, the real biological particles have different shapes and geometries. On the other hand, in the case of biological particles, according to their softness and damping properties, elastic assumption can lead to inevitable errors in simulations. So, in this paper new viscoelastic contact model applicable for different geometries has been developed and applied in force indentation simulations. Results show good compatibility with experimental data. Moreover, topography images showed that cell surface is not smooth and contains asperities, so, new viscoelastic roughness theory has been also developed for these particles with different geometries. Outputs of this model have been also compared with experimental data which showed results' modification. Application of these models in manipulation of biological cells can help to obtain more accurate results.