Energy harvesting from stray power-frequency magnetic field employing a piezoelectric unimorph based heterostructureWei He, Yueran Lu, Jitao Zhang, Chiwen Qu, Gaofeng Che and Jiancai PengEur. Phys. J. Appl. Phys., 73 3 (2016) 30903DOI: https://doi.org/10.1051/epjap/2016150599