Electrochemical Impedance Spectroscopy (EIS) of ion sensors Direct modeling and inverse problem solving using the Nernst–Planck–Poisson (NPP) model and the HGS(FP) optimization strategy

The Nernst–Planck–Poisson (NPP) model is used to numerically simulate electrochemical impedance spectra (EIS) of ion-selective electrodes (ISEs). By using the Hierarchical Genetic Strategy with real number encoding (HGS(FP)) the reverse problem is solved. The NPP–HGS(FP) method allows estimation of physicochemical parameters of ISEs with plastic membranes, which is illustrated here by using NPP–HGS(FP) for obtaining the values of the diffusion coefficients of ions in the ISE membrane phase. The NPP–HGS(FP) method allows calculation of the most accurate solution of the inverse problem and can be effectively used to facilitate the process of finding the parameters for optimal ISE performance. The method presented here not only allows for interpretation of the EIS spectra but also for accounting for the mechanism of the processes occurring at the interface in terms of physicoelectrochemically valid concepts.