Characterization of a TMR sensor for EC-NDT applications

Non-destructive tests based on eddy currents (EC-NDT) are one of the inspection techniques used to detect and characterize defects in conductive structures. The EC-NDT technique is based on the induction of eddy currents in the material under test and on the analysis of the reaction magnetic field that is generated. In this way, it is possible to detect the presence of a defect and evaluate its geometric characteristics. Generally,magnetic sensors such asAMRor GMRcan be used to detect the reaction magnetic field. Recently, magnetic field sensors based on the Tunnel effect (TMR) have been introduced, which seem to have better performances than previous solutions. In this context, the article illustrates the metrological characterization of a TMR sensor for EC-NDT applications, as the information provided by the manufacturer is not complete and sufficient for this type of use. The results obtained show that the TMR sensor is able to provide a higher sensitivity than the AMR and GMR sensors, with a limited measurement uncertainty. This makes it possible to assume that the TMR sensors can be usefully used in EC-NDT applications.