Vesicle electrohydrodynamics

TL;DR

This paper develops a perturbation analysis to understand how a uniform electric field influences lipid vesicle dynamics in shear flow, revealing shape transformations and motion stabilization effects.

Contribution

It introduces a small amplitude perturbation model incorporating electric, hydrodynamic, and membrane stresses to analyze vesicle behavior under electric fields.

Findings

Electric fields can induce shape transitions from oblate to prolate.

Electric fields damp vesicle tumbling, promoting tank-treading.

Shape evolution depends on the relative conductivity of internal and external fluids.

Abstract

A small amplitude perturbation analysis is developed to describe the effect of a uniform electric field on the dynamics of a lipid bilayer vesicle in a simple shear flow. All media are treated as leaky dielectrics and fluid motion is described by the Stokes equations. The instantaneous vesicle shape is obtained by balancing electric, hydrodynamic, bending, and tension stresses exerted on the membrane. We find that in the absence of ambient shear flow, it is possible that an applied step--wise uniform DC electric field could cause the vesicle shape to evolve from oblate to prolate over time if the encapsulated fluid is less conducting than the suspending fluid. For a vesicle in ambient shear flow, the electric field damps the tumbling motion leading to a stable tank-treading state.