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Fluid Dynamics Seminar

Monday, October 6th, 2008, 4:00 PM
Cullimore Lecture Hall, Room 611
New Jersey Institute of Technology

Electrohydrodynamic deformation of lipid bilayer membranes

Petia Vlahovska

Thayer School of Engineering, Dartmouth College

Abstract

I will present an analytical theory to explain the experimentally-observed shapes of vesicles made of lipid bilayer membrane in AC electric fields [1].

The model treats the inner and suspending media as lossy dielectrics, and the membrane as an ion-impermeable flexible incompressible-fluid sheet. The vesicle shape is obtained by balancing electric, hydrodynamic, and bending stresses exerted on the membrane.

The theory predicts that stationary vesicle deformation depends on field frequency and conductivity conditions. If the inner fluid is more conducting than the suspending medium, the vesicle always adopts a prolate shape. In the opposite case, the vesicle undergoes a transition from a prolate to oblate ellipsoid at a critical frequency, which the theory identifies with the inverse membrane charging time. At frequencies higher than the inverse Maxwell-Wagner polarization time, the electrohydrodynamic stresses become too small to alter the vesicle's quasi-spherical rest shape. The analysis shows that the evolution towards the stationary vesicle shapes strongly depends on membrane properties such as viscosity. The model can be used to rationalize the transient and steady deformation of biological cells in electric fields.

[1] Aranda et al. Biophys. J. 95 L19-21 (2008)