In this work, we present our novel planar micro-thermoelectric generators (µTEGs) integrating an original “folded” thermopile topology, periodically distributed on suspended membranes. The thermopile integrates eco-friendly and low-cost materials as Constantan (Cu55Ni45) and Chromel (Ni90Cr10) that build up thermocouples associated both in series and in parallel. This dual association allows to drastically reduce the thermopile electrical resistance (down to a few tens to a few hundred ohms) and so to electrically better adapt them. To optimize the structural dimensions of the µTEG, numerical simulations have been performed by 3D-finite element modeling using COMSOL Multiphysics© software. Several µTEG modules integrating this folded thermopile have been manufactured using Silicon micro-technologies that differ from our former expertise. In 3-membrane-based modules the harvested output power can reach 108 µW/cm2 (for 1 W heat injected into the µTEG) with an output voltage up to few hundred of millivolts, which is enough to supply micro devices for IoT applications.