Magnetoelectric and Enhanced Magneto-Mechano-Electric Cantilever Beam Devices for Harvesting Weak Magnetic Fields

This article presents the design and fabrication of magnetoelectric (ME) coupling cantilever beam devices and enhanced magneto-mechano-electric (MME) coupling cantilever beam devices for potential applications in wireless sensor networks (WSNs). The ME cantilever beam device, composed of directionally solidified FeGa alloy and PZT piezoelectric ceramics, exhibits a high-ME coupling coefficient of 156.2 V/(cm
$\cdot $
Oe) at its resonance frequency when combined with a dc bias magnetic field. It also demonstrates a maximum ME output power of 0.21 mW under a weak ac magnetic field of 1.40 Oe. Furthermore, the MME cantilever beam devices with tip mass exhibit enhanced weak magnetic field coupling ability at zero dc bias magnetic field due to the stress concentration (SC) effect. The superposition of the magnetic torque and the ME bending moment caused by the magnetostrictive layer leads to the MME device with a tip magnet mass of 18 g shows an approximately 100 times increase in output voltage compared with the device without a tip mass. These findings indicate the potential of ME and MME devices in serving as micropower sources for WSNs by detecting and harvesting stray weak ac magnetic fields.