Low-Frequency Electromagnetic Energy Harvesting

Abstract

The demand for portable permanent sources of electrical energy increases every day to power portable or non-accessible devices. Energy harvesting from vibrations offers a non-traditional source of energy. It is renewable and prevailing, since nature around is rich in kinetic energy that can be harvested.

In this work, we have developed two mechanisms to harvest energy from low-frequency vibrations present in nature using electromagnetic transduction. The harvesting mechanisms use a mass-on-spring mechanical oscillator to capture kinetic energy from a host body. Prototypes embodying the two harvesting mechanisms were fabricated and tested. We identi ed the system parameters of the harvester prototypes and generated their frequency-response curves. We analyzed the results using and compared them with mathematical models of the system dynamics to characterize the harvesters' performance including their output power, center frequency, and harvesting bandwidth.

We were successful in demonstrating energy harvesters that can harvest low-frequency vibration with center frequencies in the range of 8-14 Hz, harvesting bandwidth in the range of 8-12Hz, and output power on the order of 1mW. The realized harvesters are relatively small, a few inches in dimension, and light, a few tens of grams in mass. We also introduced a novel electromagnetic transduction mechanism that can be used in harvesting low-frequency vibrations.