Demonstration of a piezoelectric energy harvester using laterally aligned $BaTiO_3$ nanowire arrays with extremely high aspect ratio

Abstract

This paper reports demonstration of laterally aligned $BaTiO_3$ nanowire arrays with high aspect ratio for piezoelectric energy harvester.

Nanowire structure for piezoelectric energy harvester have attraction in terms of superior me-chanical properties, high sensitivity to small forces, synchronized piezoelectric effect. For the optimization of nanowire structure for piezoelectric energy harvester, implementation of high aspect ratio and alignment of nanowires are important.

Here, in order to implement perfectly aligned $BaTiO_3$ nanowires with high aspect ratio on the flexible substrate, advanced fabrication process is proposed. Proposed fabrication method is based on a 400 nm period Si nano-grating template, double etching process with metal sacrificial layer and UV curable resin for adhesive layer. All over the transferred surface ($1.5 cm \times 1.5 cm$), perfectly aligned $BaTiO_3$ nanowire arrays with high aspect ratio (over 2000:1) are realized through the proposed fabrication method.

We demonstrate the energy harvester which converts movement of a human finger into electrical energy. The measured values $(V_{OC} = 9 V and I_{SC} = 300 nA)$ are improved than that of recent previous piezoelectric nano-generators.

Laterally aligned $BaTiO_3$ nanowire arrays with high aspect ratio have been transferred onto flexible substrate for the first time. These flexible piezoelectric energy harvester have been shown to be efficient electro-mechanical energy converts, representing a promising step toward the implementation of wearable energy harvester.