Encountering Spurious Elements in Electrical Impedance Spectroscopy Data Fitting

The aim is to present situations in which collected impedance spectrum analysis data contain information that reflects not only the studied sample, but pertains also to the fundamental instrument properties or to the method in which the data is fitted or evaluated. Fitting of such data can lead to spurious, phantom elements in equivalent circuits and to frustration in data fitting. While illustrative experiments were done on specific instruments, the conclusions are generic and apply to any instrument with current supplying and potential probing inputs. The described spurious response stems from the existing unavoidable impedance of the reference inputs and from additional resistance, such as reference electrodes, connected to the inputs. Additionally is discussed a purely mathematical situation, when response artifacts are generated from correct impedance spectrum data, but incorrectly applied algebraic treatment.