Bringing better bandwidth and power density for wireless sensor networks

With the rapid development of the Internet of Things (IoTs), wireless sensor networks and miniature low-power electronics are becoming increasingly prevalent features of everyday life. Although they use very little energy, ensuring reliable power for these devices is challenging.

Currently, stray magnetic fields in the natural environment represent the best energy source. However, conventional magnetic energy harvesters (EHs) have limited energy conversion efficiency around their resonance frequency, which causes narrow bandwidths and restricts their applicability in environments with stray magnetic fields.

To address this issue, You et al. produced a novel EH with beryllium bronze/Pb(Zr,Ti)O₃ dual-beam structures that demonstrated remarkable improvements in both coupling ability and bandwidth.

“By incorporating an internal magnetic-coupled (IMC) mechanism, the bandwidth of the proposed energy harvester has been expanded by 131%,” said author Yang Shi. “Additionally, the output voltage experiences a significant improvement of 44.4%.”

Experimental investigations confirmed the superior performance of the IMC-EH, with a maximum RMS output power density of 56.25 µW·Oe^-2·cm^-3, which easily surpasses those of existing magnetically coupled piezoelectric energy harvesters.

“Notably, even under a low magnetic field of 1 Oe, the proposed IMC-EH exhibits a total output power of 185 µW, capable of continuously powering 26 LEDs in real-time,” said Shi. “This highlights its potential as a promising solution for low-power consumption in small electronics.”

The study’s findings may help inspire future design of self-powered wireless sensor networks and low-power electronics within the realm of the IoT.

“The utilization of the IMC-EH opens up possibilities for autonomous and sustainable operation of low-power devices, contributing to the advancement of energy harvesting technologies,” said Shi.

Source: “Improving the performance of low-frequency magnetic energy harvesters using an internal magnetic-coupled mechanism,” by Zhixiong You, Huining Miao, Yang Shi, and Michael Beer, Journal of Applied Physics (2024). The article can be accessed at https://doi.org/10.1063/5.0195091 .