Elevating DEP Analysis: A Rigorous Model for Small Biological Particle Manipulation

Dielectrophoresis (DEP) has emerged as a promising candidate for the manipulation and study of small biological particles. Over the years, several analytical models aiming to describe the DEP response of such particles have been presented. However, these models break down when the characteristic length of the system becomes too small, and the effects of the Electric Double Layer become significant. A notable case being Liposomes in the 50-500 nm range that are often used for drug delivery applications. To address these issues a continuum modeling approach to the simulation of the DEP response of Liposomes is presented. The steady-state solution of the Poisson-Nernst-Planck (PNP) system of equations is supplemented with a perturbative study of the response to an AC field, aiming to correctly represent the frequency response of the system. The results show good agreement with analytical models in their range of validity while simultaneously providing a more rigorous standpoint to analyze systems with smaller characteristic lengths, where the results of the approximate models become dubious. Furthermore, an attempted extension of the model with the Stokes equation is introduced, highlighting the difficulties involved with taking into account fluid flow around the particle.