Design, Fabrication, and Testing of Hybrid Energy Harvesting Units

The increasing usage of mobile electrical units demands higher energy efficiencies for these devices. Self-sustaining units that harvest various forms of ambient energy can help significantly with their regular battery replacements. In this chapter two hybrid energy harvesting units are proposed that employ piezoelectric, magnetostrictive, and electromagnetic technologies to capture ambient vibrational energy. The first harvester is made of piezoelectric and magnetostrictive materials while the second harvester is composed of a piezoelectric layer and a magnet. Both proposed harvesters employ a spiral piezoelectric layer in order to reduce the compliance of the piezoelectric unit. The advantages of the first design is that it allows for more efficient harvesting over a wider range of frequencies than traditional harvesting units while the second design reduces the natural frequency of the system that results in better energy harvesting at low frequencies.