Window effect of pulsed electric field on biological cells

Based on multilayer dielectric model, for the spherical biological cell subjected to pulsed electric field (PEF), an equivalent circuit model is presented. Frequency-domain analysis shows that inner and outer membranes exhibit band-pass and low-pass filter characteristics in response to PEF, respectively. Therefore, different biomedical effects will be induced by the field with different frequency spectrum. The method to calculate the transmembrane potentials induced by time-varying PEF is introduced, and the relationship between rectangular pulse and transmembrane potentials is also discussed. It is found that because of different charging time constants, different durations have selective effects on inner and outer membranes. The analyses in both the frequency-domain and time-domain show a window effect of PEF on biological cells. When duration is reduced from microsecond to submicrosecond, and to nanosecond, the target induced is changed from the outer membrane to the inner membrane gradually. The window effect gives preliminary explanation for various bioelectric effects such as electroporation, intracellular electro manipulation and nanopores, providing help to the applications of PEF in tumor treatment.