Magnetoelectric MEMS Magnetic Field Sensor Based on a Laminated Heterostructure of Bidomain Lithium Niobate and Metglas

Abstract

Non-contact mapping of magnetic fields produced by the human heart muscle requires the application of arrays of miniature and highly sensitive magnetic field sensors. In this article, we describe a MEMS technology of laminated magnetoelectric heterostructures comprising a thin piezoelectric lithium niobate single crystal and a film of magnetostrictive metglas. In the former, a ferroelectric bidomain structure is created using a technique developed by the authors. A cantilever is formed by microblasting inside the lithium niobate crystal. Metglas layers are deposited by magnetron sputtering. The quality of the metglas layers was assessed by XPS depth profiling and TEM. Detailed measurements of the magnetoelectric effect in the quasistatic and dynamic modes were performed. The magnetoelectric coefficient |α32| reaches a value of 492 V/(cm·Oe) at bending resonance. The quality factor of the structure was Q = 520. The average phase amounted to 93.4° ± 2.7° for the magnetic field amplitude ranging from 12 to 100 pT. An AC magnetic field detection limit of 12 pT at a resonance frequency of 3065 Hz was achieved which exceeds by a factor of 5 the best value for magnetoelectric MEMS lead-free composites reported in the literature. The noise level of the magnetoelectric signal was 0.47 µV/Hz1/2. Ways to improve the sensitivity of the developed sensors to the magnetic field for biomedical applications are indicated.

Magnetoelectric Effect in Amorphous Ferromagnetic FeCoSiB/Langatate Monolithic Heterostructure for Magnetic Field Sensing

“…The obtained value of EMND 0.36 pT/Hz 1/2 for the proposed ME structure is comparable to the noise level of 1 pT/Hz 1/2 in the AlN/Metglas structure at the resonance frequency of 860 Hz [25] and lower than the noise level of 12 pT/Hz 1/2 in the LiNbO 3 /Metglas structure at a resonance frequency of 3 kHz [27] and 60 pT/Hz 1/2 in the AlScN/Metglas structure at a resonance frequency of 8 kHz [24]. However, the EMND is highly dependent on frequency, and in future works, the frequency modulation technique can be used to increase sensitivity to low frequency magnetic field [33].…”

Magnetoelectric Functionality of Ni–Mn–In-Encapsulated AlN/Ni–Mn–In/Ni-Graded Heterostructure for Flexible Magnetic Field Sensor

“…35 The single crystal lithium niobate (LiNbO 3 ) coupled with the Metglas layer was explored as ME MEMS devices. 36 Moreover, quartz and gallium arsenide have also been introduced as lead-free piezoelectric layers in ME heterostructures to study the ME effect. 37 Aluminum nitride (AlN) has been a potential piezoelectric material owing to its complementary metal-oxide-semiconductor (CMOS) compatibility, high acoustic velocity, significant piezoelectric voltage coefficient, and low voltage operation toward various applications such as memory devices, piezoelectric actuators, and sensors.…”

“…The ME composite comprising a lead-free piezoelectric plate of monocrystal langatate was investigated for the ME magnetic field sensor . The single crystal lithium niobate (LiNbO 3 ) coupled with the Metglas layer was explored as ME MEMS devices . Moreover, quartz and gallium arsenide have also been introduced as lead-free piezoelectric layers in ME heterostructures to study the ME effect .…”