Trends in electrochemical impedance spectroscopy involving nanocomposite transducers: Characterization, architecture surface and bio-sensing

Electrochemical Impedance Spectroscopy (EIS) has gained widespread application for the characterization of functionalized electrode surfaces and for the transduction of bio-sensing events. However, bio-sensors using EIS detection have to be carefully designed to minimize non-specific binding of the analyte. In this sense, surface engineering by using nanocomposite materials (NCs) is advantageous due to the increased electrode surface area, improved electrical conductivity of the sensing interface, chemical accessibility to the analyte and electroanalysis. Accordingly, this review summarizes the basis of the EIS technique as well as its implementation not only in common Faradaic EIS (impedimetric) bio-sensors using NCs as highly sensitive transducer platforms but also in not so conventional non-Faradaic EIS (capacitive) approaches. Finally, it is also highlighted the feasibility of EIS as an alternative characterization tool towards the optimization of NC electrodes in terms of loading ratios for electroanalytical improvements, summarizing the latest promising results in nanocomposite carbon paste electrodes.