A Magneto-Mechano-Electric Generator Using Dual Piezoelectric Single Crystal Macro-Fiber Composites for a Low-Intensity Magnetic Field

Magneto-mechano-electric (MME) generators capable of efficiently converting stray magnetic fields into electrical energy have received substantial interest due to their potential for powering Internet of Things (IoT) sensor systems. However, achieving sufficient power output at low magnetic field intensities (≤ 1.0 Oe) remains a challenge for the continuous operation of IoT sensors. To address this limitation, an MME generator is developed featuring dual piezoelectric single crystal macro-fiber composites (SFCs), strategically applying two stress-concentrated regions created by heavy tip-end and middle magnets in a cantilever structure. This design produced a total root mean square power output of 0.326 mW·cm^−3·Oe⁻² at an optimal load resistance under a low magnetic field intensity of 1.0 Oe. Remarkably, even under an extremely low magnetic field intensity of 0.1 Oe, the harvested energy sustained the continuous operation of a temperature/humidity sensor and enabled the reliable performance of multi-functional IoT sensors capable of monitoring temperature, humidity, and sound. This research not only presents an effective design for harvesting energy from low-level magnetic fields but also highlights the practicality of MME generators within IoT-enabled wireless sensor networks.