Increased piezoelectric energy harvesting from human footstep motion by using an amplification mechanism

In this paper, we propose a piezoelectric energy harvester to scavenge the impact energy from human footsteps at low input frequencies. The device consists of an amplification mechanism and piezoelectric bimorphs. When a human foot strikes the proposed harvester, the amplification mechanism deforms the piezoelectric bimorphs in the 31-mode to produce a large mechanical strain, meaning that the output power can be generated with high efficiency. A maximum output power of 27.5 mW was generated by the proposed harvester at an input frequency of 1.5 Hz (representing fast walking), while 18.6 mW was generated at 1.0 Hz (representing slow walking). Comparison experiments also showed that the proposed harvester can produce much a higher output power than that the same harvester operating in the 33-mode under the same working conditions. (C) 2014 AIP Publishing LLC.