A Nail-size Piezoelectric Energy Harvesting System Integrating a MEMS Transducer and a CMOS Interface Circuit

Piezoelectric vibration energy harvesting has drawn much interest to power distributed wireless sensor nodes for Internet of Things (IoT) applications where ambient kinetic energy is available. For certain applications, the harvesting system should be small and able to generate sufficient output power. Standard rectification topologies such as the full-bridge rectifier are typically inefficient when adapted to power conditioning from miniaturized harvesters. Therefore, active rectification circuits have been researched to improve overall power conversion efficiency, and meet both the output power and miniaturization requirements while employing a MEMS harvester. In this paper, a MEMS piezoelectric energy harvester is designed and cointegrated with an active rectification circuit designed in a CMOS process to achieve high output power for system miniaturization. A MEMS energy harvester of 0.005 cm size, co-integrated with the CMOS conditioning circuit, outputs a peak rectified DC power of 40.6μW and achieves a record DC power density of 8.12mW/cm when compared to state-of-the-art harvesters.