In this paper, we present a solution for leadless pacemakers electrical supply based on inertial piezoelectric micro-generator that would allow the harvesting of a portion of the vibrational energy of the heartbeat. Based on the analysis performed on real cardiac signals, we have proposed the harvester optimal frequency range centered at 16 Hz. Constrained by this low frequency and small device size, we have defined the structure optimal dimensions requiring piezoelectric layers thicknesses in the range of tens of micrometers. The device optimal dimensions mainly resulted from an optimization that highlights the need for a new PZT layers fabrication technology. We present the work that has been done to develop a thick film fabrication technique (typ. 15 to 100 µm) by thinning thick layers of PZT. Finally, we show that the fabricated demonstrator vibrating at 16 Hz converts the electrical power from heartbeats reproduced in a laboratory experiment fulfills the requirements  (10 - 15 μW) for the implementation of an energy supply solution for leadless pacemakers.