Piezoelectric transformer based ultrahigh sensitivity magnetic field sensor

Magnetoelectric particulate composites with varying ferrite content (3-20 mol %) were synthesized in the system Pb (Zr0.52 Ti0.48) O3 (PZT) - Ni0.8 Zn0.2 Fe2 O4 (NZF) and it was found that 0.8PZT-0.2NZF composite material exhibited high response of the order of 450 mVcm Oe at the low frequency of 1 kHz with 600 Oe dc bias. This is one of the highest magnitudes reported for the sintered particulate composite materials. This material was used to fabricate a magnetic field sensor which utilizes the piezoelectric transformer structure with ring/dot electrode pattern. The size of the magnetic field sensor was φ20×1.5 mm2. The sensor was characterized for the changes in the output voltage and resonance frequency shift under constant current condition. A dramatic change in the magnitude of the output voltage and frequency shift was observed on application of the magnetic field. The sensor design presented in this letter clearly shows the possibility of fabricating an extremely cost-effective magnetometer.