Energy Harvester based on Piezoelectric Impact Compartment

Disclosed is an energy harvester for generating electric energy from an external vibratory force, such as a vibratory force caused by movement of a part of a living human or animal. The energy harvester has a compartment (CMPI, CMP2) with wall element(s) forming a cavity inside. At least one wall element of the compartment has a piezoelectric element connected to an elec­tric output terminal. An impact object (BL) is positioned inside the cavity of the compartment. The impact object is configured to move inside the cavity and to generate an impact on a surface of the wall element(s), so as to cause the piezo­electric element to generate an electric output on the electric output terminal. The compartment may have a cubic shape, e.g. made of a single piezoelectric element folded into shape, e.g. a two-layer piezoelectric element. The impact object may be a metal or ceramics object with a spherical shape. Especially, the energy harvester may be used to power an implantable medical device, e.g. an intra-cardiac pacemaker. An energy harvester housing within an intra-cardiac pacemaker has been tested to be snfficient for powering the pacemaker stimu­lation circuit by the vibratory force caused by heartbeats.