Fabrication and Characterization of High-Performance Polymer-Based Magnetoelectric DC Magnetic Field Sensors Devices
The development of a DC magnetic field sensor based on a magnetoelectric (ME) PVDF/Metglas composite is reported. The ME sensing composite has an electromechanical resonance frequency close to 25.4 kHz, a linear response (r<sup>2 </sup> = 0.997) in the 0–2 Oe DC magnetic field range, and a maximum output voltage of 112 mV (ME voltage coefficient α<sub>33</sub> of ≈30 V·cm<sup>−1</sup>·Oe<sup>−1</sup>). By incorporating a charge amplifier, an AC-RMS converter and a microcontroller with an on-chip analog-to-digital converter, the ME voltage response is not distorted, the linearity is maintained, and the ME output voltage increases to 3.3 V (α<sub>33effective</sub> = 1000 V·cm<sup>−1</sup>·Oe<sup>−1</sup>). The sensing device, including the readout electronics, has a maximum drift of 0.12 Oe with an average total drift of 0.04 Oe, with a sensitivity of 1.5 V·Oe<sup>−1</sup> (15 kV·T<sup>−1</sup>), and a 70 nT resolution. This feature is for the first time reported on a polymer-based ME device and compares favourably with a reference Hall sensor that showed a maximum drift of 0.07 Oe and an average error of 0.16 Oe, 5 V·T<sup> −1</sup> sensitivity, and 2 μT resolution. Such properties allied to the accurate measurement of the DC magnetic field (H<sub>DC</sub>) in the 0–2 Oe range make this polymer-based device very attractive for applications, such as Earth magnetic field sensing, digital compasses, navigation, and magnetic field anomaly detectors, among others.