Tunable MEMS piezoelectric energy harvesting device

This work is focused on low frequency (<300 Hz) vibrations due to the fact that many industrial and commercial devices operate at those frequencies. The aim of the present work is to model by numerical simulation a Si cantilever beam with an AlN piezoelectric layer concept that tunes its resonant frequency post-processing, while reducing the separation of the first two modes of resonance in order to broaden its quality factor and, therefore, to harvest more environmental energy. This paper investigates by numerical simulation the influence of perforating sections of the Si beam has on the resonant frequencies of the cantilever. The authors have found that the distance between these modes is decreased by 30 % when 0.002 mm³ is extracted in a specific location of the initial structure. This difference between modes can be reduced above 80 % if a volume of 0.004 mm³ in a specific part of the initial design is subtracted. In these conditions, the first mode is decreased about 20 % the initial value and the second mode about 60 %.