A simple Arduino-based EIS system for in situ corrosion monitoring of metallic works of art

Metallic artifacts of archaeological and historical interest, exposed outdoor, can be severely affected by degradation due to the exposure to aggressive agents present in the surrounding environment. Development of suitable preventing conservation strategies for these important witnesses of our culture, requires to investigate their corrosion behavior in order to understand the electrochemical phenomena occurring on the metallic surface. This investigation can be easily performed in laboratory by means of different chemico-physical techniques, which provide information about composition, microstructure and morphology of the corrosion products, as well as by means of electrochemical measurements, which allow estimating the corrosion resistance of the metal. Unfortunately, these measurements are often invasive and require microsampling. Electrochemical Impedance Spectroscopy (EIS), thanks to the high sensitivity and to the small perturbation applied to the corroding system, can be considered a useful non-destructive testing method to obtain valuable information on the conservation state of metallic works of art. This paper describes an innovative portable, low-cost and user-friendly solution for EIS in situ measurements, based on the widely diffused Arduino board and on a specially designed measuring probes. The proposed solution cannot provide the complete knowledge of the corrosion mechanisms occurring onto the metallic surface, but can be an extremely useful tool for conservators and art historians for the assessment and long-time monitoring of the artifacts stability.