A unimorph piezoelectric cantilever generator with an interdigitated electrode (IDE) was developed for vibration energy harvester applications driven in the longitudinal mode. Hard lead zirconate titanate (PZT) ceramic with a high Q_m of 1,280 was used as the piezoelectric active material. Ten PZT sheets produced by tape casting were laminated and co-fired with an Ag/Pd IDE at 1,050℃ for 2 h. The approximately 280 μm-thick co-fired PZT laminate with the IDE was attached to a stainless steel substrate with an adhesive epoxy for the fabrication of an IDE unimorph cantilever. Its energy harvesting characteristics were evaluated: an output power of 1.1 μW at 120 Hz across the resistive load of 700 k□ was obtained, corresponding to a normalized power factor of 4.1 μW/(G²·cm³).

We fabricated piezoelectric unimorph cantilever generators (UCG) using Pb(Zr0.54Ti0.46)O3 + 0.2 wt% Cr2O3 + 1.0 wt% Nb2O5 (PZCN) piezoelectric thick films, which were produced by a tape casting method. The PZCN thick films were tailored with same width and thickness but different lengths from 7.7 to 57.7 mm in order to evaluate optimized UCG for energy harvesting device applications. When the length of PZCN film was increased, the resonance frequency of UCG was slightly increased from 7 Hz to 8 Hz, which could be due to enlarged area of the highly stiff piezo-ceramic film. However, the output power was proportionally increased with the length of PZCT film and it reached 4.68 mW (1.221 mW/cm3) when the film`s length was 57.7 mm under 25 g of tip mass at 8 Hz, which is sufficient for micro-scale device applications.