Speaker
Description
The increasing demand for energy harvesting is associated with the current era of big data, when a problem of power supply of numerous distributed sensors must be addressed. A recent research attention has been paid to ferrofluids in the role of a nanogenerator’s active medium. Efforts have been put in development of ferrofluid-based triboelectric nanogenerators and piezoelectric energy harvesters. However, ferrofluids have gained recognition primarily for their great potential in electromagnetic energy harvesting systems, utilizing the basic principles of electromagnetic induction. In contrast to conventional electromagnetic generators that rely on solid moving magnets, ferrofluids enable creation of generators of light-weight, smaller size and flexible shapes.
In our study, we have prepared five ferrofluid samples based on biodegradable transformer oil. The ferrofluids with different iron oxide nanoparticle concentrations were subjected to investigation of vibrational energy harvesting utilizing the ferrofluid sloshing (volume of 2.5 ml). This enables us to obtain the dependence of the electromotive force on the ferrofluid magnetization of saturation. We also study the electromagnetic induction by ferrofluid sloshing in various magnetic field configurations. The ferrofluid sloshing is excited by a laboratory shaker and the induced voltage is studied under both, increasing and decreasing shaking rates (frequency). It is found that the most effective energy harvesting is achieved in the magnetic field of 15 mT generated by a single permanent magnet attached to the ferrofluid vial side wall, providing the field intensity perpendicular to the axis of the vial motion and gravity. The maximal mean power achieved with the ferrofluid is 233 nW. In conversion, it is 93 nW per milliliter of the ferrofluid. The increasing magnetization of saturation yields the increase in the harvested power except of the ferrofluid sloshing in the magnetic field of the single magnet attached to the bottom of the horizontal vial, when the opposite effect is observed. The dependence of the mean induced voltage on the vial oscillation frequency is identical for measurements in acceleration and deceleration mode and this behavior holds for each magnetic field configuration and each ferrofluid concentration.
Acknowledgements
This work is funded by Slovak Academy of Sciences and Ministry of Education in the framework of projects VEGA 2/0029/24, and Slovak Research and Development Agency under the contract No. APVV-22-0115.
