Low-frequency non-periodic vibrations are sought to be a promising energy source for wearable sensors as well as for environmental/structural monitoring. However, conventional resonant harvesters cannot accommodate the required operation bandwidth and large internal displacement range. In this project, we developed a piezoelectric frequency increased generator, which utilizes an internal bi-stable mechanism that up-converts the ambient random vibration frequencies to a higher internal operation frequency. This architecture incorporates a fixed internal displacement while achieving high electromechanical conversion efficiency and large bandwidth. The fabricated device could be suitable for various wearable electronics application, as it generates a peak power of 100 μW and an average of 3 μW over a wide frequency range of 1-24 Hz, and has a compact package of 2.8 cm3.
T. Galchev, E. E. Aktakka, K. Najafi, “A piezoelectric parametric frequency increased generator for harvesting low frequency vibrations,” IEEE/ASME J. of Microelectromechanical Systems, vol. 21, pp. 1311-1320, 2012. [PDF]
T. Galchev, E. E. Aktakka, H. Kim, K. Najafi, “A piezoelectric frequency-increased power generator for scavenging low-frequency ambient vibration” in IEEE International Conf. on Micro Electro Mechanical Systems (MEMS’10), Hong Kong, PRC, pp. 1203-1206, Jan. 2010. [PDF]