Sensitivity of Thin Film Magnetoimpedance Sensor in 0.3 T Surface Normal Magnetic Field.

Detection of foreign matters and nanoparticles included in industrial and chemical products is an important application target for a sensor system. There is a need to detect a small piece of steel tool chipping or breakage included in the products nondestructively. A recent improvement of the manufacturing system strongly required an inspection of all items in every production process to realize the smart manufacturing system. A thin‐film magnetic field sensor is an impressive candidate for this target as it has an extremely high sensitivity, especially because it is driven by alternating current around hundreds of MHz, and it is also tolerant to a surface normal magnetic field due to its demagnetizing force in the thickness direction. In this study, the sensitivity of a sensor system that was created by applying a 0.3 T normal field to the detection area included in a sensor element and also by using a 400‐MHz high‐frequency driven thin‐film magnetoimpedance sensor was evaluated. An observation of the magnetic domain was also carried out at the same time as the sensitivity evaluation. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]