Development of differential hall sensors for Pulsed Eddy Current Testing using Gaussian pulse excitation

This study presents the use of differential Hall sensors in Pulsed Eddy Current Testing with Gaussian pulse excitation. This method was selected for its ability to effectively distribute energy across the frequency spectrum, thereby enhancing inspection depth and precision compared to the conventional rectangular pulses. The design of the differential Hall sensors, which includes two Hall sensors, greatly minimizes interference from the primary magnetic field, resulting in improved accuracy in detecting defects, particularly corrosion, across varying lift-off distances. 3D-FEM simulations and experimental results demonstrate that differential Hall sensors outperform traditional single Hall sensors in reducing noise and maintaining corrosion signal. Compared to traditional single Hall sensors, the differential Hall sensors exhibit a significantly improved signal-to-noise ratio, particularly at larger lift-off distances. Additionally, the study employs the Full Width at Half Maximum method to accurately estimate the size of corrosion, offering a precise and non-invasive approach to assessing structural integrity.