Integrated power harvesting system including a MEMS generator and a power management circuit

This paper presents a novel ambient energy scavenging system for powering wireless sensor nodes. It uses a MEMS generator and an ASIC power management circuit. The system is created as a System on a Package with all components fabricated entirely using microfabrication techniques. Its performance is compared with standard approaches using a resistive load or discrete Schottky diodes. The electromechanical transduction is performed using the piezoelectric effect of aluminium nitride thin films. The reported experimental results prove the possibility of exploiting very low amplitude signals delivered by the generator for charging a storage capacitor. It is also shown that a system of 5 mm3 can endlessly power a simple wireless sensor node; while a lithium polymer thin film battery of the same volume can do so only for less than 2 months.