A piezoelectric cantilever energy harvester (PCEH) driven in longitudinal (3-3) vibration mode was fabricated, and its electrical properties were evaluated by varying the resistive load. A commercial PZT piezoelectric ceramic with a high piezoelectric charge constant (d₃₃) of 520 pC/N and the interdigitated (IDT) electrode pattern was used to fabricate the PCEH driven in longitudinal vibration. The IDT Ag electrode embedded piezoelectric laminates were co-fired at 850℃ for 2 h. The 3-3 mode PCEH was successfully fabricated by attaching the piezoelectric laminates to a SUS304 elastic substrate. The PCEH exhibited a high output power of 3.8 mW across the resistive load of 100 kΩ at 100 Hz and 1.5 G. This corresponds to a power density of 10.3 mW/cm³ and a normalized global power factor of 4.56 mW/g²·cm³. Given the other PCEH driven in transverse (3-1) vibration mode, the 3-3 mode PCEH could be better for vibration energy harvesting applications.

Piezoelectric thick films of a soft Pb(Zr,Ti)O₃ (PZT) based commercial material were produced by a conventional tape casting method. Thereafter, the interdigitated (IDT) Ag-Pd electrode pattern was printed on the 25 ㎛ thick piezoelectric film at room temperature. Co-firing of the 10-layer laminated piezoelectric thick films was conducted at 1,100℃ and 1,150℃ for 1 h, respectively. Piezoelectric cantilever energy harvesters were successfully fabricated using the IDT electrode pattern embedded piezoelectric laminates for 3-3 operation mode. Their energy harvesting characteristics were investigated with an excitation of 120 Hz and 1 g under various resistive loads (ranging from 10 kΩ to 200 kΩ). A parabolic increase of voltage and a linear decrease of current were shown with an increase of resistive load for all the energy harvesters. In particular, a high output power of 3.64 mW at 100 kΩ was obtained from the energy harvester (sintered at 1,150℃).