Biomimetic membranes in electric fields: capacitive charging and stability

Cells and cellular organelles are encapsulated by nanometrically thin membranes whose main component is a lipid bilayer. In the presence of electric fields, the ion-impermeable lipid bilayer acts as a capacitor and supports a potential difference across the membrane. We analyze the dynamics of a planar membrane separating bulk solutions with different electrolyte concentrations in an applied uniform DC electric field. The membrane is modeled as a zero-thickness capacitive interface. The evolution of the evolution potential and ions distributions are solved for using the Poisson-Nernst-Planck equations. Asymptotic solutions are derived in the limit of thin Debye layers and weak fields (compared to the thermal electric potential). The effect of the field on the thermal fluctuations of a membrane is also considered.