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)

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