Electrokinetic behavior of two touching inhomogeneous biological cells and colloidal particles: Effects of multipolar interactions

TL;DR

This paper develops a theoretical model to analyze how multipolar interactions influence the electrokinetic behavior of touching inhomogeneous biological cells and colloidal particles under AC fields, revealing significant effects on their spectra.

Contribution

It introduces a comprehensive theory incorporating multipolar interactions and internal inhomogeneities for predicting electrokinetic responses of complex particles.

Findings

Multipolar interactions significantly affect electrokinetic spectra.

Inhomogeneities within particles influence their polarization behavior.

The model reproduces known results in the point-dipole limit.

Abstract

We present a theory to investigate electro-kinetic behavior, namely, electrorotation and dielectrophoresis under alternating current (AC) applied fields for a pair of touching inhomogeneous colloidal particles and biological cells. These inhomogeneous particles are treated as graded ones with physically motivated model dielectric and conductivity profiles. The mutual polarization interaction between the particles yields a change in their respective dipole moments, and hence in the AC electrokinetic spectra. The multipolar interactions between polarized particles are accurately captured by the multiple images method. In the point-dipole limit, our theory reproduces the known results. We find that the multipolar interactions as well as the spatial fluctuations inside the particles can affect the AC electrokinetic spectra significantly.