A mechanism of skin appendage macropores electroactivation during iontophoresis.

A physical mechanism of activation of skin appendage macropores under the influence of an electric field is considered theoretically. The macropore is considered as a long cylinder tube which is closed and flattened out before the electric field is applied. The charging of the capacitance of the macropore walls is the driving force of electroactivation. During this process the free energy of the system decreases, which is energetically favourable and results in water pulled into the tube and to a gradual opening of the tube. It is shown that consideration of the macropore wall conductance leads to a considerable slowdown of electroactivation. The opening time of a separate macropore is estimated. It is equal to 30 min for a macropore 4 mm in length. The dependence of the surface density of activated macropores on time is calculated theoretically. The obtained theoretical results are in a good agreement with the literature data.