Enhanced Flexible Magnetoelectric Composites Based on BN-Doped P(VDF-TrFE) for AC Magnetic Sensing

Flexible magnetoelectric (ME) composites made of flexible piezoelectric materials are more applicable to more complex applications, such as wearable smart devices and implantable medical devices. However, flexible piezoelectric materials, such as PVDF, typically have weaker piezoelectric properties compared to piezoelectric ceramics. Therefore, this paper improved the piezoelectricity of P(VDF-TrFE) films by doping boron nitride (BN). The piezoelectric coefficient d<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</sub> was raised to 43 pC/N, compared to ~30 pC/N of pure P(VDF-TrFE) films and the commercial PVDF films. BN doped P(VDF-TrFE) films were then used as the piezoelectric phase to prepare flexible magnetoelectric composite materials with FeSiB. The DC bias magnetic field and the size of the composites were optimized to increase the magnetoelectric coupling coefficient (α<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ME</sub>) to 72.2 V/cm·Oe at 40.22 kHz with a bias magnetic field (H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub>) of 5 Oe, which was 30.3% higher than that of the pure P(VDF-TrFE)/FeSiB composites. The bending performance of the ME composite materials were also studied. When the bending angle reached 70°, the ME coupling coefficient was still 7.1 V/cm·Oe. Finally, the sensing characteristics of the AC magnetic sensor based on the BN doped P(VDF-TrFE) ME composites were investigated, and the device demonstrated good linearity, repeatability, and hysteresis. The proposed flexible ME composites, which incorporated BN doped P(VDF-TrFE), demonstrated significant potential for applications in flexible sensors.