Optimization of electroporation waveforms for cell sterilization

Pores occur naturally in cell membranes. Application of an electric field generates a force which tends to open the pore, a mechanism known as electroporation. The force generated depends on the electric field in the pore and the difference in dielectric constant between the fluid in the pore and the membrane. In this paper, we use transient finite-element analysis to investigate the field as a function of time in a system which consists of an electrolyte, an ellipsoidal bacterial cell membrane, and cytoplasm within the cell membrane. For this shape of cell, the field in the cell membrane is caused largely by the relaxation of the field in the cytoplasm. In addition, we compute the force on the pore wall, both in an analytic approximation and numerically as a function of time during a variety of applied voltage waveforms, using transient finiteelement analysis. The numerical data are in good agreement with the analytic approximation and provide a basis for judging the efficacy of waveforms for sterilization based on a "figure of merit" which is suggested in the paper.