This letter presents a high performance bimorph piezoelectric MEMS harvester with bulk PZT thick films on both sides of a flexible thin beryllium-bronze substrate via bonding and thinning technologies. The upper and lower PZT layers are thinned down to about 53 μm and 76 μm, respectively, and a commercial beryllium bronze with the thickness of about 50 μm is used as the substrate. The effective volume of this device is 30.6 mm³. The harvester with a tungsten proof mass generated the close-circuit peak-to-peak voltage of 53.1 V, the output power of 0.979 mW, and the power density of 31.99 mW/cm³ with the matching load resistance of 360 kΩ at the applied acceleration amplitude of 3.5 g and the applied frequency of 77.2 Hz. Meanwhile, in order to evaluate the stability, the device was measured continuously under applied acceleration amplitudes of 1.0 g and 3.5 g for one hour and demonstrated a good stability. Then, the harvester was utilized to light up LEDs and about twenty-one serial LEDs were lighted up at resonance under an applied acceleration amplitude of 3.0 g.

Tire pressure monitoring system (TPMS) has been brought into the stringent regulatory frameworks of many countries in the automotive market. However, common commercial TPMSs must rely on a life-limited battery, which brings about some safety risks and environmental problems. It is worthy to note that energy harvesting approaches are promising to realize a batteryless TPMS. Here, a rotation-driven piezoelectric energy harvester with eight typical nonlinear buckled-bridges is proposed to effectively scavenge ultralow-frequency kinetic energy. Thinned bulk PZT film is employed as the piezoelectric functional layer based on its excellent electromechanical factor. Gear induced inter-well oscillation mechanism ensures the effective deformation of the piezoelectric buckled-bridges. The developed harvester can generate the effective output power of 8.9 mW under the optimal resistance of 3 kΩ at 8.3 Hz rotational frequency. The 47, 100 and 330 μF capacitors can be saturated at 14.5, 15.1 and 14.5 V during 10 s, 19 s and 51 s, respectively. Additionally, a commercial TPMS can be effectively powered by this harvester when it works at more than a critical frequency locating at 3.0 to 3.7 Hz. The commercial TPMS can be operated in real time when the applied rotational frequency is more than 8.3 Hz.