Printed Piezoelectric Harvester for Integration in a Wearable Energy Storage Device

Energy storage and harvesting technologies are intricately linked. Various technologies have been developed to convert environmental energies into electricity. For instance, piezoelectric nanogenerators (PENGs) capture mechanical motion/vibration energy. Additionally, efforts have been directed towards integrating these energy harvesting devices into flexible/wearable units suitable for wearable electronics. This study showcases a printed flexible piezoelectric energy harvester with PVDF-TrFE and silver electrode, organized as a double-sided coating onto the polyethylene terephthalate (PET) substrate, thus forming the front side electrode for the PENG and backside electrode for a storage thin film element. A dielectric film of Al2O3 and the top electrode of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)/ graphene composite are applied by printing, realizing layer-by-layer assembly. The capabilities of the energy harvesting devices were characterized by a one-point eclipsed bending test, and the experimental results are presented to substantiate the potential utility of the fabricated device. This method provides a more controlled and uniform loading scenario for accurate testing without dependence on the sample length. It was found that loading of 100 g/cm² produces a symmetric electrical signal with a magnitude of ~ ±0.4 V from a sample with an area of 2.5 cm². This voltage is sufficient to drive the charging of a sample supercapacitor, which will be investigated further.