High-sensitivity magnetic sensor based on the evanescent scattering by a magnetorheological film

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)6643-6646
Number of pages4
Journal / PublicationOptics Letters
Issue number24
Online published8 Dec 2020
Publication statusPublished - 15 Dec 2020


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 ∼ 2.62 dB/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.