Designing and manufacturing a piezoelectric tile for harvesting energy from footsteps

The objective of this research is to design a piezoelectric tile for harvesting energy from footsteps and to optimize the system for harvesting maximum energy. Because piezoelectric modules easily break when directly subjected to energy generated by human movements, we designed a tile that employs indirect energy transmission using springs and a tip mass. We aimed at matching the mechanical resonance frequency of the tile with that of the piezoelectric modules. The resonance frequency of a piezoelectric module with a 10-g tip mass was almost similar to the vibration frequency of the tile at 22.5 Hz when we dropped an 80-g steel ball from a 1-m height. We performed impedance matching and realized a matching value of 15 kΩ. Under these optimal mechanical and electrical conditions, we harvested 770-μW RMS and 55-mW peak output power.