Particle interactions in three-dimensional electrical field simulated by iterative dipole moment method

Abstract

The dielectrophoresis (DEP) interactions of a few particles in a uniform two-dimensional (2D) electrical field have well been studied by Maxwell stress tensor (MST) method. Multiple particle interactions in three-dimensional (3D) electrical field are investigated in this work using iterative dipole moment (IDM) method which is an analytic algorithm without complicated numerical computations to solve for electrical field. The interactive DEP forces of particles calculated by IDM are found to be well agreed with those of MST method and much simple to implement. Using IDM method, a series of examples of multiple particles interactions and particle chains in a 3D uniform DC electrical field is presented. Randomly distributed similar dense particles (either all positive DEP (pDEP) or all negative DEP (nDEP) particles) in 3D uniform electrical field can generally form chains in lines parallel to the electrical field, except the case that all similar particles are in a plane perpendicular to the electrical field where the particles repel each other and move away in the plane. Randomly distributed dissimilar dense particles (mixture of pDEP and nDEP particles) can form (1) chains in lines, (2) clusters in a plane or (3) 3D groups. The chains, clusters and groups are of staggered arrangements of pDEP and nDEP particles, which are perpendicular to the electrical field.