Materials, Methods & Technologies, Volume 12, 2018

Abstract: In this paper, we demonstrate fabrication of environmental friendly flexible piezoelectric generator and propose optimization strategy for its performance by a formation of stress concentrators in the piezoelectric material. The entire structure is characterized with improved electrical response to mechanical stimuli, although the thickness of the used piezoelectric film is in nanosized range. Piezoelectric oxide films are grown by vacuum sputtering and patterned in a specific way by applying lift-off microfabrication technology. The design is based on simulation analysis, showing a concentration of peak stress in specific areas, causing enhanced charge generation. As a result, the piezoelectric coefficient of 11.28 pC/N is achieved and it is superior, compared to the device without concentrators. This value is competitive to devices using lead-containing lead zirconium titanate (PZT), as well as to devices with millimeter thickness of the piezoelectric material. Vibrational dynamic test in the low- frequency range up to 50 Hz shows that the generated voltage after patterning increases with 12.8 %, reaching ~677 mV. In addition, the device with concentrators can stand 187 000 bends without failure and the useful capacity, which is greater than 250 pF, decreases by 7%.