Zinc oxide/aluminum-based self-powering storage system fabricated using selectively direct-write ultraviolet-curable resin method

This article presents a flexible piezoelectric harvester based on a polyethylene terephthalate cantilever system to scavenge vibration energy. It comprises a low-voltage drop rectifying circuit and an electrolytic capacitor to store the induced voltage. The harvester was made in the form of a composite plate that consists of flexible aluminum/polyethylene terephthalate vibration plate, piezoelectric zinc oxide thin film, and selectively deposited ultraviolet-curable resin lump structures as proof mass, which were directly constructed on the rear side of the polyethylene terephthalate-based composite plate using electrospinning with a stereolithography technique. Aluminum was sputtered on the polyethylene terephthalate substrate as the bottom electrode because of superior adhesion with the polyethylene terephthalate and zinc oxide film, compared with indium tin oxide film. Finite element analysis simulations were used to analyze the operation frequency and output voltage of the piezoelectric composite plate. The experimental results show that the maximal open-circuit voltage was 2.4 V and the close-circuit voltage was 2.18 V, which is 0.56 µW/cm ² . After rectification, a direct current voltage of 2 V across the capacitor can be achieved. The self-powered storage system can drive the warning signal of the light-emitting diode module in both resonant and nonresonant conditions.