Fast impedance analyser for corrosion monitoring

Frequency Response Analysers (FRA) are commonly employed to monitor the corrosion state of metallic antiquities. Commercial devices, though very accurate and versatile, are often rather costly and require a long time to complete the Electrochemical Impedance Spectroscopy (EIS). This paper describes a low cost and portable alternative to commercial FRAs that also embeds the potentiostatic function and therefore can be used in the field without requiring external devices. The proposed instrument is based on a compact DSP board and employs a sine-fit algorithm for the impedance measurement; the paper also describes a fast algorithm to obtain the results without requiring long measuring sessions. The proposed instrument automatically performs a simple coating test and is equipped with a digital interface so that it can be connected to a personal computer to carry out a complete frequency analysis and to perform more complex data processing.