An Optical Sensing Strategy for Passive Magnetic-Field Measurement in IoT-Enabled Renewable Energy Systems

Intelligent sensing technologies are increasingly integrated into modern society to support a wide range of functions. Among these technologies, magnetic-field sensing plays a pivotal role in domains such as industrial diagnostics, geophysical exploration, biomedical imaging, etc. While, conventional magnetic field sensors often suffer from limited precision, restricted sensitivity, and active measurement, which constrain their broader deployment. In this study, a sensing strategy is introduced that employs an optical interferometric structure to measure Lorentz-induced deformation in an electromechanical coupling material, thereby achieving magnetoelectric conversion and the measurement of a magnetic field. This sensing strategy enables passive operation with a resolution of 178 μT and a sensitivity of 56.2 pm/mT. These results are validated by the magnetoelectric voltage measurement, showing a consistency of R² = 0.978. Additionally, the method of integrating a functional film increases the sensitivity by 1.8 times. Moreover, this approach is promising to extend to various piezoelectric and metal materials, thereby making contributions for the development of energy-autonomous sensing systems, magnetomechanical transducers and actuators, electromagnetic pollution monitoring, and biomedical applications.