Development of a Sustainable and Flexible Piezoelectric-cum-Triboelectric Energy Harvester Comprising a Simple Commodity Cotton Fabric

Abstract

Herein, a fully sustainable, flexible, and bio-based piezoelectric-cum-triboelectric energy harvester has been developed using a simple commodity cotton fabric. In the present study, a novel attempt has been made to prepare a piezoelectric and triboelectric energy harvester in a combined manner from the same fabric substrate. The developed mercerized cotton fabric-based energy harvester has shown a significant open-circuit peak-to-peak voltage of ∼47 V and current of ∼1 μA, simply by finger tapping (under a higher amount of pressure). The same device generated an open-circuit peak-to-peak voltage and short-circuit current of 1.77 V and 100 nA, respectively, in response to impact forces (20 N at 7 Hz frequency) applied using a customized force-imparting device. The reason for the enhanced energy of the device made of mercerized fabric has been correlated with structural characteristics of the fabrics. The piezoelectric response of the cotton fabric-based energy harvester has been observed mainly due to the strong intramolecular and intermolecular hydrogen bonds present in the cellulose chains. These strong hydrogen bonds act as strong dipoles inside the cotton fabric structure, for which the resultant dipole moment is very high. On the other hand, triboelectric response of the device is primarily due to the charges developed at the interfaces of a highly electropositive aluminum electrode and highly electronegative polypropylene (PP) of the respective encapsulated devices as per triboelectric series. The developed piezoelectric-cum-triboelectric energy harvester can successfully be utilized as an efficient wearable to power small-scale electronic gadgets.