A Magnetic Sensor Based on a Coil Probe for Electromagnetic Non-Destructive Testing

Electromagnetic Non-Destructive Testing (NDT) Applications, such as Magnetic Flux Leakage and Magnetic Barkhausen Noise, offer high sensitivity but are limited by the low spatial resolution of traditional sensors like induction coils and Hall elements. While Magnetic Force Microscopy based on magnetic probe achieves nanoscale resolution, its performance is hindered by interference from strong background magnetic field during excitation. This work proposes a novel coil probe sensor, integrating a closed coil onto a traditional Atomic Force Microscopy probe. The micrometer-scale coil probe achieves high spatial resolution and suppresses interference from static background magnetic field, enabling accurate detection of dynamic magnetic field. Experiments and simulations validate its capability in detecting magnetic field distributions around defects, with coil size and lift-off distance identified as key influencing factors. The proposed probe offers a robust solution for high- spatial resolution electromagnetic NDT application.