Non-linear time domain model of electropermeabilization: Effect of extracellular conductivity and applied electric field parameters

The simulated results indicate that it may be difficult for cells of substantially different sizes to be close to uniformly electroporated if surrounded by media with a conductivity higher than around 5×10-3S/m for 100 kHz bipolar pulses, or 0.2 S/m for 1 MHz bipolar pulses. To achieve as normalized as possible electroporation for the radii/size variation required in any particular application, using a lower σe would be preferable. There is, however, a limit to how low the external conductivity can be made, as the applied electric field amplitude must stay within practical limits. Considering 3×1013pores/m2 as a nominal pore density N for approximately optimum electroporation, σe could be as low as 0.08 S/m for a 7.5μm cell radius with a peak electric field of 1.2×105V/m (depending on the pulse shape and frequency). For a 15μm cell radius, σe could be as low as 0.05 S/m (depending on the pulse shape and frequency). It is seen that the relative difference of N between the two cell sizes investigated is consistently lower for a bipolar sine wave electric field compared to a bipolar square wave electric field, even though the square wave electric field peak amplitude is always lower for an equivalent N.