Maximizing power generation from ambient stray magnetic fields around smart infrastructures enabling self-powered wireless devices†
Harvesting electrical energy from stray magnetic fields is appealing for development of a sustainable power source for Internet of Things (IoT) devices that are being implemented in the smart infrastructure. Stray magnetic fields are ubiquitous in buildings, but have fixed frequency (50/60 Hz) and low amplitude. Magnetoelectric (ME) coupled magneto-mechano-electric (MME) energy conversion is the most efficient way to convert these low frequency stray magnetic fields into electricity. However, currently reported ME coupled MME generators produce high output power only under relatively strong magnetic fields (≥500 μT), which are not available under practical conditions. Here a novel ME coupled MME generator has been demonstrated that provides 400% higher output power compared to the state-of-the-art, when operating below magnetic field levels of 100 μT. The optimized ME coupled MME generator produces milliwatt power below 300 μT stray magnetic field. The output power from extremely low magnetic fields (≤50 μT) is sufficient to power hundreds of light emitting diode (LED) arrays and operate a digital clock without charging a capacitor. By exploiting the harvested power near a home appliance, sustainable powering of sensors and a wireless communication system is demonstrated. Fundamental advancements from this work will provide a direction for deploying ME and MME generator driven self-powered IoT devices in smart infrastructures.