The instrumentation is based on the electrical resistivity tomography (ERT) which is a non-invasive geophysical technology used to obtain information on anomalous bodies possibly present in the subsoil. The theoretical basis lies in the different electrical properties of the lithotypes present in the subsoil. Starting from these considerations it is possible to shift the interest of applicability both on structures related to cultural heritage by creating a miniaturized portable instrumentation capable of being adapted both to situations in which highly resistive structures are analyzed (built heritage, frescoes, mosaics , etc.) and when analyzing structures with medium-low resistivity values (trees, wooden beams, structures buried in the marine environment, etc.). The instrumentation can also be adapted to the diagnostics of large infrastructures (bridges, tunnels, etc.).
The instrumentation object of the invention involves the use of non-invasive electrodes that are made to adhere to the body to be investigated; a system that regulates the choice of current electrodes and potential electrodes; a system that regulates the injection of the current and the measurement of the potential difference; a computer with acquisition software and subsequent data processing. The instrument is equipped (innovative part) with an intelligent system capable of adjusting the output impedance and consequently adapting the contact resistance between the electrode and the material to be investigated. This allows the injection of current even in very resistive materials (frescoes, mosaics, masonry structures, statues, columns, etc.). A second system inserted in the instrumentation (innovative part) also allows to carry out measurements of spontaneous potential. This latter point is important in the study of the state of corrosion of the bars located in reinforced concrete structures (large infrastructures, bridges, tunnels, etc.). The possibility of increasing the number of electrodes allows the realization of 3D tomographies.