Impedance Spectroscopy of Water Solutions:  The Role of Ions at the Liquid−Electrode Interface

Abstract

We discuss the influence of the ions dissolved in a liquid on the impedance spectroscopy of a cell. Our analysis is performed in the small-voltage regime, where the actual bulk density of ions is only slightly perturbed by the external electric field. In this framework, we show that the presence of the ions can be taken into account by a surface density of charge. The agreement between the theoretical prediction, on the basis of the assumption that the ionic mobility is frequency independent, and the experimental data for the real and imaginary parts of the impedance is fairly good for frequencies larger than 100 Hz. In the low-frequency range, the agreement of the theory with the experiment is rather poor. In this region, the experimental data can be successfully fitted by introducing the impedance of the metal-electrolyte interface, which is accurately represented by Zi = w(i omega)(-nu), where w and nu are two constants, with 0 < nu < 1. From the analysis of the experimental data, we determine w and nu. The theoretical predictions of our model are in good agreement with the experimental data in the investigated frequency range.

Application of a Coaxial-Like Sensor for Impedance Spectroscopy Measurements of Selected Low-Conductivity Liquids

“…On the top plot of the figure, the real and imaginary parts of the impedance as measured by the LCR meter are shown as functions of frequency. One can compare this spectrum to the results reported in [2], where the KCl aqueous solution of a concentration of 0.6 mM was examined in the frequency range 5 Hz–10 MHz. As can be seen, even in a narrower frequency range, which was applied in the present study, all relevant features of the spectrum are evident, including the impact of the electrode-electrolyte interface impedance modeled in this work by the constant phase element.…”

“…For example, in [2], an experimental cell designed for impedance spectroscopy measurements of low-conductivity liquids in the frequency range of 5 Hz to 10 MHz was presented. However, precise measurements of inhomogeneous or highly viscous materials in a broad frequency range put some special requirements on the design of a sensor.…”

Impedance Study of Dopamine Effects after Application on 2D and 3D Neuroblastoma Cell Cultures Developed on a 3D-Printed Well

“…In general, a wide frequency range is preferred in order to improve the efficiency in impedance measurements [42]. The impedance interface of the metal-electrolyte plays a fundamental role in the low frequencies (<100 Hz) [43]. This information can be helpful for medicine evaluation that interfere DA's absorption from cells, since the activation of D2-like receptors has been associated with inhibition of cAMP accumulation [44].…”

Traceability of electrolytic conductivity measurements to the International System of Units in the sub mSm−1 region and review of models of electrolytic conductivity cells

“…• analytical models obtained for simple cell geometries and accounting for the accumulation of ions at the electrodes by means of the Stern model [57]; • coupled models, based on the numerical or analytical determination of electrolyte resistance and electrode capacitance and on the successive inclusion of the double layer capacitance according to the Gouy-Chapman-Stern model [40,42]; • analytical or numerical models, which incorporate the contributions of polarisation and finite ion size following modified Poisson-Boltzmann theories [19,56,[58][59][60].…”