Keywords: nanofibers, piezoelectric, energy harvesting, electrospinning
Summary:As the demand for renewable energy increases worldwide, so to does the demand for wearable and autonomous robots that can act as actuators and sensors. The inventions and improvements that have been made in the field of piezoelectric nanofibers has opened the door to a world of innovations in the space of wearable, energy harvesting clothing, namely through nanofiber yarns. On their own, piezoelectric nanofibers tear easily when stretched because of the low inter-friction parameters; this is an issue because to achieve a piezoelectric response out of the nanofibers, they must be stretched and then poled. However, twisting the nanofibers into a yarn increases the friction force between nanofibers, which allowed the nanofibers to be stretched beyond their normal tearing point. Additionally, the piezoelectric nanofibers naturally become aligned and poled as they are stretched as a yarn; this combination of twisting the nanofibers into a yarn and aligning the nanofibers in the beta-phase allows for a poling-free piezoelectric yarn manufacturing method. Once the piezoelectric nanofibers are twisted into yarns and aligned and poled, they can be woven into a variety of textiles that, when worn by a person or machine, will naturally have a piezoelectric response. The piezoelectric response can be harnessed and stored in the textile, and utilized as a battery free motion detector in smart garments. The combination of twisting and naturally aligning and poling of piezoelectric nanofibers serve as a strong basis for the future of wearable energy harvesting textiles.