Magnetically Polarizable Energy-Efficient Magnetoelectric Core-Shell Nanocomposites for Magnetic Field Sensing

This article reports an energy-efficient method of magnetic poling for core-shell magnetoelectric (ME) nanoparticles with cobalt ferrite (CoFe2O4) nanoparticles as core and barium titanate (BaTiO3) shell embedded in polydimethylsiloxane (PDMS) matrix for the development of low-cost, flexible, magnetic field sensors. The simplicity in fabrication, high sensitivity magnetic field detection, low-frequency operation capability, and a unique magnetic poling approach, projects it as an alternate to the current state-of-the-art magnetic sensors. The trielectrode configuration of the proposed sensor enables a directional magnetic sensing by either d(31) or d(33) operating modes, which shows the comparable performances of electrically poled and magnetically poled sensor variants. This article reports a sensitivity of 16.20 and 16.86 mV/Oe, for the electrically and magnetically poled variants in d(31) mode, respectively, while the sensitivities of 12.5 and 13.7 mV/Oe are obtained in d(33) mode for electrically poled and magnetically poled variants, respectively. The underlying physics for the equivalence of two types of poling is explained using piezoforce microscopy (PFM), magnetic force microscopy (MFM) techniques, and different structural characterizations. The persistent issues in electrical poling are addressed, and the resulting high-performance magnetically poled core-shell nanocomposite sensors are projected for unprecedented applications in wearable sensing, soft robotics, and smart health monitoring.