Fabrication and Characterization of High-Performance Polymer-Based Magnetoelectric DC Magnetic Field Sensors Devices

Abstract

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 (r2 = 0.997) in the 0–2 Oe DC magnetic field range, and a maximum output voltage of 112 mV (ME voltage coefficient α33 of a30 V·cm−1·Oe−1). 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 (α33effective = 1000 V·cm−1·Oe−1). 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−1 (15 kV·T−1), 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 −1 sensitivity, and 2 μT resolution. Such properties allied to the accurate measurement of the DC magnetic field (HDC) 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.