T-shaped Piezoelectric Vibratory MEMS Harvester with Integration of Highly Efficient Power Management System

This paper introduces a T-shaped piezoelectric vibratory MEMS energy harvester. The prototype measurement results clearly demonstrate that the T-shaped harvester can achieve higher normalized power efficiency by a factor of 1.95 in comparison with the conventional piezoelectric harvester. Since the magnitude of harvested voltage in this type of energy harvesters is only a few millivolts, utilizing the traditional power electronic components is impractical. Thus, in this paper we also propose a highly efficient power management system without requiring external bias voltages. The numerical simulation illustrates that our proposed power management system can rectify and boost the harvested voltage up to 5V. In order to keep the output voltage on the load side at a stable level, a JFET transistor is utilized as a voltage limiter. Thus, the processed output voltage cannot exceed 4V even if a higher harvested voltage may be produced by the harvester. (paper)