A magnetic field fiber optic sensor with magneto-optic polymers and nanoparticle core-shell polymers

Miniaturized magnetic field sensors have become increasingly important in various applications, such as geophysical exploration for minerals and oil, volcanology, earthquake studies, and bio-medical imaging. Existing magnetometers lack either the required spatial or the temporal resolution or are restricted to costly shielded labs and cannot operate in an unshielded environment. Increasing the spatio-temporal resolution would allow for real-time measurements of magnetic fluctuations with high resolution. Here we report on a new nanocomposite-based system for miniaturized magnetic field sensing. The sensor is based on Dy3+ -doped magnetite and cobalt ferrite nano-particles dispersed in a polymer matrix. Operation has been demonstrated at room temperature and in an unshielded environment. A compact fiber-optic interferometer is used as the detection mechanism with 20 fT/Hz sensitivity. We investigated the magnetic field response of the sensor and demonstrated the measurement of the human heartbeat as a potential application. ©2019 Old City Publishing, Inc.