Theoretical analysis of localized heating in human skin subjected to high voltage pulses.

Electroporation, the increase in the permeability of bilayer lipid membranes by the application of high voltage pulses, has the potential to serve as a mechanism for transdermal drug delivery. However, the associated current flow through the skin will increase the skin temperature and might affect nearby epidermal cells, lipid structure or even transported therapeutic molecules. Here, thermal conduction and thermal convection models are used to provide upper and lower bounds on the local temperature rise, as well as the thermal damage, during electroporation from exponential voltage pulses (70 V maximum) with a 1 ms and a 10 ms pulse time constant. The peak temperature rise predicted by the conduction model ranges from 19 degrees C for a 1 ms time constant pulse to 70 degrees C for the 10 ms time constant pulse. The convection (mass transport) model predicts a 18 degrees C peak rise for 1 ms time constant pulses and a 51 degrees C peak rise for a 10 ms time constant pulse. The convection model compares more favorably with previous experimental studies and companion observations of the local temperature rise during electroporation. Therefore, it is expected that skin electroporation can be employed at a level which is able to transport molecules transdermally without causing significant thermal damage to the tissue.