Equilibrium electrodeformation of a spheroidal vesicle in an ac electric field

摘要

In this work, we develop a theoretical model to explain the equilibrium spheroidal deformation of a giantnunilamellar vesicle (GUV) under an alternating (ac) electric field. Suspended in a leaky dielectric fluid, thenvesicle membrane is modeled as a thin capacitive spheroidal shell. The equilibrium vesicle shape results fromnthe balance between mechanical forces from the viscous fluid, the restoring elastic membrane forces, and thenexternally imposed electric forces. Our spheroidal model predicts a deformation-dependent transmembranenpotential, and is able to capture large deformation of a vesicle under an electric field. A detailed comparisonnagainst both experiments and small-deformation (quasispherical) theory showed that the spheroidal model givesnbetter agreement with experiments in terms of the dependence on fluid conductivity ratio, permittivity ratio,nvesicle size, electric field strength, and frequency. The spheroidal model also allows for an asymptotic analysisnon the crossover frequency where the equilibrium vesicle shape crosses over between prolate and oblate shapes.nComparisons show that the spheroidal model gives better agreement with experimental observations.