Electret-based aeroelastic harvester and its self-starting battery-free power management circuit

This paper presents an airflow energy harvester coupling (i) fluttering phenomena to turn airflows kinetic power into mechanical oscillations of a flexible membrane and (ii) an electret-based electrostatic converter to turn the resulting mechanical oscillations into electricity. The device is able to work down to 5.5m/s and harvests up to 330μW at 9m/s with a surface of 70mm×55mm. It has been combined to a self-starting battery-free power management circuit to supply a Bluetooth Low Energy temperature sensor node, validating the complete Energy Harvesting chain. The power management circuit implements the Synchronous Electric Charge Extraction technique with a flyback architecture; it has a conversion efficiency reaching 60% and consumes about 1.2μA.