Piezoelectric thick films of soft Pb(Zr,Ti)O3 (PZT) based commercial material (S55) were fabricated using a conventional tape casting method. Ag-Pd electrodes were printed on the piezoelectric film at room temperature and all 5 layered films with a dimension of 12 ㎜× 16 ㎜were successfully laminated for a multi-layered piezoelectric ceramic actuator. The laminated specimens were co-fired at 1,100℃ for 1 h. A flat layered and dense microstructure was obtained for the 112 ㎛thick piezoelectric actuator after sintering process. Thereafter, a prototype piezoelectric speaker was fabricated using the multi-layered piezoelectric ceramic actuator which can operate as a bimorph. Its SPL (sound pressure level) characteristic was also evaluated for speaker application. Frequency response revealed that the output SPL with a root mean square voltage of 10 V increased gradually to the highest peak of 87.5 dB for 1.5 kHz and exhibited a relatively stable behavior over the measured frequency range (≤20 kHz) at a distance of 10 cm, implying that the fabricated piezoelectric speaker is potential for speaker applications.

Citations

• Development of Shoe-heating System based on Piezoelectric Energy Harvesting
  Seung-Jin Lee, Sang-Woong Lee, Hi-Geun Shin, Gi-Man Kim, Seong-Dae Choi
  Journal of the Korean Society of Manufacturing Process Engineers.2019; 18(7): 48.     CrossRef

A new water energy harvester module, which is composed of piezoelectric bimorph cantilevers, harvesting circuit and a shaft with 16 impellers at a center axis, was fabricated for energy harvesting application. High energy density Pb(Zr0.54Ti0.46)O3 + 0.2 wt% Cr2O3 + 1.0 wt% Nb2O5 (PZT-CN) thick film obtained by tape casting method was used for the bimorph cantilever. The PZT-CN bimorph cantilever with a proof mass of 49 g exhibited extremely high output power of 22.5 mW (24 mW//cm3) at resonance frequency of 11 Hz. In addition, the fabricated water energy harvester has a cylindrical structure with 48 bimorph cantilevers clamped at inner surface. A significantly high output power of 433 mW was obtained at a rotation speed of 120 rpm with a resistive load of 500 Ω for the water energy harvester.

Spring supported piezoelectric cantilever structures (SPCS) were fabricated for vibration-based energy harvester application. We selected four elastic springs (A, B, C, and D type) as cantilever`s supporter, each elastic spring has a different spring constant (S). The C type of SPCS (SC: 4,649 N/m) showed a extremely low resonance frequency of 81 Hz along with the highest power output of 38.5 mW while the A type of SPCS (SA: 40,629 N/m) didn`t show a resonance frequency while. Therefore, it is considered that the lower spring constant lead to a lower resonance frequency of the SPCS. In addition, a tip mass (18 g) at one end of the SPCS could further reduce the resonance frequency without heavy degradation of power output.

Citations

• Feasibility study for the self powered wireless emergency call button using electromagnetic energy harvesting mechanism
  Il-Jung Kim, Yeon-Suk Choi
  Journal of the Korea Safety Management and Science.2014; 16(2): 111.     CrossRef
• A Study on the Characteristic of Energy Harvesting Mechanism for Batteryless Wireless Switch
  Yeon-Suk Choi
  Journal of the Korea Academia-Industrial cooperation Society.2014; 15(5): 3114.     CrossRef