Floating potentials appear in electrokinetic problems when isolated high conductive materials are included in a dielectric or weakly conductive ambient medium. The large contrast of conductivities generates numerical issues that make hard the computation of the electric potential. The paper proposes a rigorous numerical method to tackle such kind of problems. Interestingly, a correction to the case of perfect conductor is given in order to improve the accuracy of the computation. The method involves a cascade of two elementary problems set respectively in the ambient medium and in the high conductive inclusions. An example is proposed with a 4-electrode system designed to both induce electroporation in a biological tissue sample and measure the resulting impedance. The approach is extended to a nonlinear problem by taking advantage of the iterative scheme that is necessarily applied in this case.

In electromagnetism, a conductor that is not connected to the ground is an equipotential whose value is implicitly determined by the constraint of the problem. It leads to a nonlocal constraints on the flux along the conductor interface, so-called floating potential problems. Unlike previous numerical study that tackle the floating potential problems with the help of advanced and complex numerical methods, we show how an appropriate use of Steklov-Poincaré operators enables to obtain the solution to this partial differential equations with a non local constraint as a linear (and well-designed) combination of N + 1 Dirichlet problems, N being the number of conductors not connected to a ground potential. In the case of thin highly conductive inclusion, we perform an asymptotic analysis to approach the electroquasistatic potential at any order of accuracy. In particular, we show that the so-called floating potential approaches the electroquasistatic potential with a first order accuracy. This enables us to characterize the configurations for which floating potential approximation has to be used to accurately solve the electroquasistatic problem.