Tapered-Beam Piezoelectric MEMS Energy Harvesters

Tapered piezoelectric energy harvesters take advantage of the tapered beam shape but in doing so the modeling complexity is greatly increased when compared to the nominal case of a rectangular piezoelectric energy harvester. This chapter presents the various benefits that can be gained from using a tapered beam shape both in terms of its structural merits and the charge separation capacity. Owing to the added complexity in modeling tapered beams, the design of tapered energy harvesters widely uses FEM simulations instead of formulating and solving a detailed mathematical model as is possible for rectangular energy harvesters shown in Sect. 2.6.3 . To illustrate the traditional design methodology involving FEM simulations of the tapered device, the design, fabrication, and characterization steps of two generations of rectangular and tapered PEH devices are presented. The devices were fabricated at the foundry at the Institute of Microelectronics (IME), Singapore, and the design and characterization work was performed at the MEMS characterization facility at Masdar Institute (MI), Khalifa University.