Advances in the design of a gel-cell electrochemical sensor for corrosion measurements on metallic cultural heritage

Electrochemical impedance spectroscopy (EIS) is widely used in corrosion studies and coatings evaluation for metals. However, its applicability to conservation problems in the field cultural heritage is limited by the practical difficulties of performing in-situ measurements on sculptures and monuments. Authors have proposed use of a gel polymer electrolyte (GP-E) cell as an electrochemical sensor to overcome the difficulties of handling liquid electrolytes on irregular surfaces. The aim of this paper is to optimize the design of the G-PE cell for in-situ EIS measurements on metallic cultural heritage, and to characterize in detail the possible effects of the configuration of the cell on the EIS spectra. Parasitic impedances from the reference electrodes have been analyzed to discriminate the response of the working electrode from that arising from artifacts from the cell setup, in order to be able to make an accurate interpretation of the results. This has allowed optimizing the different parameters and designing an effective tool for conservation assessment in metallic cultural heritage.