The layer may either be Insulating,
Resistive (supporting electrolytes only), or an
Ion-exchange membrane.
For Resistive or
Ion-exchange membrane, the potential drop over the membrane is determined either from the
Surface resistivity or the
Thickness and conductivity.
For Ion-exchange membrane, the choice of
Charge-carrying species concentration species specifies that the current flowing over the layer will be carried by this species (which must have a nonzero charge number). The potential condition may be either
Donnan, which calculates the potential shift over the boundary based on the membrane charge carrying species concentration, or
User defined.