Development, characterization, and power management of electromagnetic-type hybrid vibro-acoustic energy harvester for wireless sensor nodes

Abstract

Vibration and acoustic energies are widely harvested for the power requirements of wireless sensor nodes (WSNs) but rarely we can see the simultaneous conversion of vibration and acoustic using a single energy harvester. To attain the self-sustained long-standing operation of WSNs, we present a novel hybrid vibro-acoustic energy harvester (HVA-EH) utilizing a spherical magnet to harvest acoustic and vibration energies at the same time. The development, characterization, and power management of the proposed HVA-EH are illustrated in this paper. The Prototype comprises of 3D printed structure, a cantilever beam with a cavity for the spherical magnet which is used to add more resonance to the system, a Helmholtz cavity (HC) and a flexible micro planar coil (FMPC). Due to base excitation, the cantilever beam vibrates and as a result, the magnet oscillates, while on the other side the acoustic waves enter the HC through its neck and oscillate the FMPC. Because of these oscillations, the FMPC experiences variation in magnetic flux and an electromotive force is generated. The device was tested under standalone vibration and acoustic environment as well as under a hybrid environment and the output parameters were noted. It was observed that when the device was exposed to a hybrid environment, the results showed enhanced output parameters and generates higher energy. By adding vibration to the standalone acoustic device, an increase of 44.72% was observed in the output power. The developed prototype was also connected to a power management circuit developed in this work, and an output DC power of 5056 μW was achieved. Additionally, a 1.5 V AAA battery was successfully charged by the HVA-EH in an hour's time duration. The output power produced by the novel HVA-EH is significant and is quite enough to operate the WSNs. This work paves a new way for developing hybrid environment-type energy harvesters for efficiency enhancement.