An inventive energy harvesting apparatus may include a ferromagnetic material and/or a shape memory alloys to convert thermal energy to mechanical energy to electrical energy. The apparatus is subjected to a thermal gradient to cause beams to bend thus creating stress/strain in a piezoelectric material or creating magnetic flux in a magnetic path. The charges created in this process can be transferred to electrical batteries. Applications: Networked systems of wireless sensor Patent Status: US7800278
Enhancement of the operating frequency by having better contact between heat sources and the energy harvesting devices.