Related Experiment Video
Updated: Nov 25, 2025

Quantifying the Relative Thickness of Conductive Ferromagnetic Materials Using Detector Coil-Based Pulsed Eddy Current Sensors
Published on: January 16, 2020
High-sensitivity magnetic sensor based on the evanescent scattering by a magnetorheological film
Abstract:
We present a simple concept to implement a magnetic sensor that uses evanescent scattering by a suspended magnetorheological (MR) film above a planar waveguide. The soft MR film embedded with ferromagnetic particles is to induce scattering on the evanescent field of a planar waveguide at a proximity distance. This distance can be controlled precisely by a magnetic field. Consequently, the waveguide output power changes in response to the magnetic intensity. Two sensor prototypes of different film thicknesses were designed and tested showing a trade-off between the sensitivity and dynamic sensing range. A maximum sensitivity of ∼2.62dB/mT was obtained. Compared to optical micro-electromechanical systems, the presented sensors feature a simple design, easy fabrication, low cost, and the potential for large-scale production and miniaturization to be integrated into portable devices.
Related Concept Videos
Ferromagnetism
Magnetic Damping
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
Magnetic Resonance Imaging
Magnetic Susceptibility and Permeability
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...

