A Miniature Magnetic-Piezoelectric Thermal Energy Harvester

Abstract

In this paper, we report a miniature thermal energy harvester with a novel magnetic-piezoelectric design. The harvester consists of a soft magnetic Gd cantilever beam, a piezoelectric PZT sheet, an NdFeB hard magnet, silicon clamps, and a silicon frame. In this design, the harvester is driven by a temperature difference between a cold side and room temperature ambient air, unlike other magnetic-piezoelectric thermal energy harvesters that are driven by a temperature difference between a cold side and a hot side or between two hot sides. Experimental results show that with a temperature difference of 20 °C (cold side: 6.7 °C, higher temperature side: 26.7 °C), the harvester produces a maximum peak-to-peak voltage of 37 mV and root-mean square voltage of 1.98 mV. The estimated maximum instantaneous power density and average power density is 21.7 nW/cm 3 and 62.9 pW/cm 3 , respectively. Moreover, the total volume of our harvester (length×width×height: 6×3.5×3 mm) is 217 times smaller than that of previous experimental harvesters and 38 times smaller than that of previous theoretical-modeled harvesters. Therefore, our harvester is the smallest machined magnetic-piezoelectric thermal energy harvester designed to date. These features enable our harvester to be more easily implemented and integrated with micro wireless-sensors and thereby increase more self-powered wireless-sensing applications.Index Terms-magnetic, thermomagnetic, piezoelectric, thermal, energy harvester, power generator 0018-9464 (c)

High-performance thermomagnetic generator controlled by a magnetocaloric switch

“…In comparison with the pretzel-like topology which also uses La(Fe, Si) 13 -based materials 18 , our TMG uses nearly 40% less La(Fe, Si) 13 -based materials but generates a 55% higher V unit and 300% higher P Dmax than the V unit of 0.022 V/g and P Dmax of 0.992 mW/cm 3 obtained by pretzel-like topology. Moreover, the P Dmax produced by our TMG is not only much higher than those of other previous TMGs 11 , 12 , 16 , 17 , 21 , 22 , but also higher than those of TEG 23 – 26 and PEG 5 , 27 , 28 . Furthermore, Fig.…”

“…In this context, we use finite element simulation to investigate the effect of key structural parameters on the magnetic circuit performance, and then fabricated a TMG device based on the optimized parameters. The experimental results demonstrate that this TMG exhibits a much higher performance than previous TMGs; 11 , 12 , 16 , 17 , 21 , 22 the max power density is 2 to 3 orders of magnitude higher than those of previous reports 12 , 17 , 21 . It also exhibits higher power density in comparison with TEG 23 – 26 and PEG 5 , 27 , 28 technologies.…”

Optimization of a Thermomagnetic Heat Engine for Harvesting Low Grade Thermal Energy

“…Andreevskil suggested a numerical model of the thermomagnetic engine that characterizes the thermodynamic and physical aspects of the system [23]. Chen et al and Chun et al introduced a GD-based thermomagnetic generator, where a cantilever beam structure was proposed to attain the spring effect [24,25]. The designed thermomagnetic generator can produce the actual work during the first half of the thermomagnetic cycle.…”