The directional motion of nano-objects induced by an inhomogeneous strain field

Recent molecular dynamics simulations have shown that an inhomogeneous strain field in a substrate could drive nano-objects to move on its surface. A theoretical model is established in this paper in order to find the mechanical mechanism from the continuum mechanics point of view, but with the help of atomic interaction potential. The substrate is represented by graphene, and the above nano-object is represented by a graphene flake or a carbon nanotube. Three typically inhomogeneous strain fields are considered, including linear, power and exponential. It was found that a driving force and a couple moment can be induced on the flat flake and the circular nanotube, respectively. Furthermore, both the driving force and the couple moment increase with the increase in strain gradient in the substrate. The size effect of nano-objects and boundary effect on the movement are also investigated in order to explain some interesting results found in the existing numerical simulations. The present theoretical study cannot only reveal the source of the driving mechanism for the movement induced by an inhomogeneous strain field but also give insights for the design of nano-transport devices.