In contemporary society, in which the population is fast aging and social infrastructure is become obsolete, technology for preemptive detection of problems is important for both safety and economic efficiency. The only way to achieve this is to “continually sense the state of target objects, such as buildings and human bodies, to accumulate data.” At present, compact sensor devices use storage batteries as a source of power, but the high cost and associated risk when changing them pose an issue. An energy harvester (which converts energy available in nature into electric energy) that replaces such batteries will be required to achieve: 1) perpetual power generation under harsh environments, 2) highly efficient power generation, 3) compactness, and 4) a low burden on the environment (i.e., the human body). One promising candidate for an energy harvester that addresses these issues is vibration-generated power technology that utilizes piezoelectric thin films’ piezoelectricity to convert vibration-generated energy into electric energy. However, it is difficult for this technology to meet all four of the requirements above because of the restrictions associated with said device’s structure and piezoelectric materials.
To find solutions to this, we have so far developed “lead-free huge piezoelectric rare earth AIN thin films” and technology for “controlling crystal orientation and polarization of AIN thin films by irradiating ions.” For this proposed research, we will combine these technologies to develop “bimorph-type piezoelectric vibrational energy harvesters made of huge polarization-inverted rare-earth-doped AIN films.”