Abstract
The effect of applied voltage (V) or a membrane-bound charge (q) on local thickness fluctuations (LTFs) in lipid bilayers is examined using the continuum approach. Ponderomotive forces, calculated from the linearized Poisson-Boltzmann equation, reduce the electroelastic energy of LTFs quadratically with V and q. Combined with a significant increase in the apex field gradient and perturbation of lipid packing at large amplitude LTFs, this creates a driving force for instability resulting in water penetration, formation of pores, and membrane rupture. The estimated critical voltages for membrane electroporation are compared with the classical Crowley prediction and recent molecular dynamics (MD) simulations. Unsolved questions impeding a full understanding of low-voltage breakdown are critically examined. Possible connections between MD results and the issue of negative capacitance and related instabilities at electrified interfaces are outlined.