The aim of this research is to study and simulate the Andrews impact theory and its potential in identifying the properties of soft biological particles and in manipulating these particles at nano scale by means of the atomic force microscope (AFM). The reason for employing the Andrews theory in this research is that this theory is unique in considering the plastic state of soft biological nanoparticles. First, the required equations for the estimation of two basic parameters (i.e., indentation depth and contact radius) used in the identification of properties and manipulation of these particles were derived. Since none of the previous works has considered the velocity of biological nanoparticles, and since the impact of biological particles with AFM tip and with substrate has been ignored in these works, the impacts between AFM tip and DNA particle and between DNA particle and substrate were simulated in this paper. The findings showed that before applying a load to a particle by a cantilever, due to the impact of AFM tip with the particle, a relatively noticeable deformation was created. This deformation, which has been disregarded in previous works up to now, can play an important role in identifying the properties of nanoparticles, in manipulation and even in controlling the cantilever of the atomic force microscope. The existing experimental results were used to validate the findings of this research.
