Introduction:  Electroporation  is  a  technique  for  increasing  the  permeability  of  the  cell  membrane  to 
otherwise  non-permeate  molecules  due  to  an  external  electric  field.  This  permeability  enhancement  is 
detectable if the induced transmembrane voltage becomes greater than a critical value which depends on the 
pulse  strength  threshold.  In  this  study,  the  variability  of  the  electric  field  threshold  and  the  minimal 
transmembrane  voltage  resulting  in  detectable  electroporation  of  the  plasma  membrane  of  spherical  and 
irregularly shaped cells have been investigated.   
Materials and Methods: Spherical cells of different dimensions and attached cells of various shapes were 
selected.  The chosen  cells  were  exposed  to  100  0s electric  pulses  with  incrementing  amplitudes. 
Electroporation was detected by an increase in the fluorescence caused by an influx of Ca 2+  and the threshold 
electric field for each cell was recorded. A 3D geometrical model of each cell was constructed from its cross 
sectional images. Simulation using the finite element method was performed to obtain the critical induced 
transmembrane voltage for each individual cell.  
Results: The magnitudes of the electric field strength threshold and critical transmembrane voltage versus 
cell radius were obtained for spherical cells. To investigate the effects of cell shapes and orientations on the 
field strength threshold and critical voltage, the considered attached cells were categorized into three different 
groups.  Field  strength  threshold  and  critical  voltage  was  obtained  for  each  cells  and  the  results  for  the 
different groups were compared.  
Discussion and Conclusion: Size, shape and orientation of cells affect the critical transmembrane voltage 
and  all  these  elements  in  turn  influence  the  electric  field  threshold  and,  therefore,  the  efficiency  of 
electroporation.