Travelling-Wave Dipolophoresis: Levitation and Electrorotation of Janus Nanoparticles

We present a theoretical study of the hydrodynamic and electrokinetic response of both metallic spherical polarized colloids as well as metallodielectic Janus particles, which are subjected to an arbitrary non-uniform ambient electric field (DC or AC forcing). The analysis is based on employing the linearized ‘standard’ model (Poisson–Nernst–Planck formulation) and on the assumptions of a ‘weak’ field and small Debye scale. In particular, we consider cases of linear and helical time-harmonic travelling-wave excitations and provide explicit expressions for the resulting dielectrophoretic and induced-charge electrophoretic forces and moments, exerted on freely suspended particles. The new analytic expressions thus derived for the linear and angular velocities of the initially uncharged polarizable particle are compared against some available solutions. We also analyze the levitation problem (including stability) of metallic and Janus particles placed in a cylindrical (insulating or conducting) pore near a powered electrode.

Thermal radiation, radiation force and dynamics of a polarizable particle in vacuum

We discuss the basic expressions and interrelations between various physical quantities describing the fluctuation–electromagnetic interaction of a small polarizable particle during relativistic motion relative to the blackbody radiation, namely, the radiation tangential force, rate of heating, intensity of thermal radiation/absorption and acceleration. We also obtain an explicit formula for the frictional force acting on the particle in its rest frame and discuss its connection with tangential force in the reference frame of the background radiation.