Relaxor Piezoelectric Single Crystal Multilayer Stacks for Energy Harvesting Transducers (RPSEHT)

Energy management is one of the most challenging issues in the world today. Accordingly, various energy harvesting technologies have gained attention, including harvesting energy from ambient vibration sources using piezoelectric materials. However, conventional piezoelectric energy harvesting transducer (PEHT) structures have effective piezoelectric constants that are lower than about 10^4 pC/N, (resonant mode). These low piezoelectric constants lead to conventional PEHTs not being able to harvest electric power effectively. Further, for a specific vibration/motion source, it would be advantageous to maximize the mechanical energy captured from the vibration structure into the piezoelectric device and to convert a greater fraction of that mechanical energy into electrical energy more efficiently. This invention is a system and method using multistage force amplification of piezoelectric energy harvesting transducers (MFAPEHTs) to increase the effective piezoelectric constant to >10^6 pC/N and to increase the mechanical energy input to the device. The invention utilizes 33 mode PZT to permit maximum coupling between the input mechanical energy with the piezoelectric material, and multilayer construction of single crystal PMN-PT material to significantly amplify the voltage/charge generation and storage from the applied mechanical force. NASA Langley Research Center has developed a system to increase the effective piezoelectric constant and the mechanical energy input to energy harvesting transducers. This results in practical performance advantages including higher mechanical-electrical coupling and conversion efficiencies, and more efficient operation across a range of vibrational frequencies.