Combined Electric and Magnetic Field-Driven Assembly of Magnetic Janus Particles

We will present results from the assembly of magnetic Janus colloids under combined (and sometimes competing) dielectrophoretic and magnetophoretic forces. While the dielectrophoretic interactions involve the electrostatic charges on the particle surfaces, the polarizability of the ionic atmosphere around them, and corresponding flows, the force exerted by the magnetic field can be independent of the dispersion medium and can be conveniently modulated in directions independent of the applied electric field. We have previously reported the assembly of metallo-dielectric Janus particles into 1D and 2D structures by controlling the magnitude and frequency of the AC electric field. By including magnetic interactions, the range of interactions, the types of possible static structures and the speed of dynamic manipulation are greatly expanded. These novel particles could serve as a tool for studying new physical phenomena and large-scale assembly, and have numerous potential applications, among which are bifunctional drug delivery agents and flexible displays.