Thermal energy harvesting based on ferromagnetic shape memory alloy microactuation

This paper presents a new principle of harvesting thermal energy at small temperature differences based on bidirectional actuation of a ferromagnetic shape memory alloy (FSMA) cantilever. The thermally induced change of magnetization of the ferromagnetic cantilever tip is used to generate a current according to Faraday´s law. The layout, fabrication and performance of a first demonstrator are shown operating at frequencies and amplitudes of 80 Hz and several hundred microns, respectively. For a pick-up coil of 1000 turns, the maximum current is about 10 μA corresponding to a power density of 0.8 μW/cm³.