Microcrack-assisted piezoelectric acoustic sensor based on f-MWCNTs/ BaTiO₃@PDMS nanocomposite and its self-powered voice recognition applications

Piezoelectric materials are suitable for use in wearable devices because of their simplicity and self-powering characteristics. However, before they can be used as wearable sensors, their flexibility and sensitivity need to be enhanced. Therefore, investing time and effort for improving piezoelectric materials is essential. In this study, we fabricated flexible piezoelectric nanogenerators (FPENGs) with microcracks based on a functionalized multi-walled carbon nanotubes/BaTiO3@polydimethylsiloxane composite. Then, we performed morphological and structural analyses of the fabricated composite. It was found that the presence of microcracks improved the output performance of the FPENG. The fabricated FPENG could function as an acoustic sensor with significantly enhanced frequency range sensitivity. As a proof-of-concept application, the ability of the FPENG to differentiate the loudness and melody of sound music, as well as its audio-to-text conversion capability, was demonstrated. These results validated the potential of the FPENG for a broader range of wireless communication applications on the Internet of Things.