Piezoelectric Fibers: Processing and Challenges

Abstract

Integration of piezoelectric materials in composite and textile structures is promising for creating smart textiles with sensing or energy harvesting functionalities. The most direct integration that combines wearability, comfort, and piezoelectric efficiency consists of using fibers made of piezoelectric materials. The latter include inorganic ceramics or organic polymers. Ceramics have outstanding piezoelectric properties but can not be easily melted or solubilized in a solvent to be processed in the form of fibers. They have to be spun from precursor materials and thermally treated afterward for densification and sintering. These delicate processes have to be carefully controlled to optimize the piezoelectric properties of the fibers. On the other hand, organic piezoelectric polymers, such as polyvinylidene fluoride (PVDF), can be spun by more conventional textile fibers technologies. In addition to enjoy an easier manufacturing, organic piezoelectric fibers display flexibility that facilitates their integration and use in smart textiles. However, organic fibers suffer from a low piezoelectric efficiency. This reviews looks at the processing techniques and their specific limitations and advantages to realize single-component or coaxial piezofibers. Fundamental challenges related to the use of composite fibers are discussed. The latter include challenges for poling and electrically wiring the fibers to collect charges under operation or to apply electrical fields. The electromechanical properties of these fibers processed by different manufacturing techniques are compared. Recent studies of structures used to integrate such fibers in textiles and composites with conventional techniques and their potential applications are discussed.

A Review on PVDF Nanofibers in Textiles for Flexible Piezoelectric Sensors

“…Usually, it is necessary to convert the nonpolar α phase into the polar β phase through thermal annealing, mechanical stretching, high-voltage polarization treatment, and so on, so that the piezoelectric properties of PVDF can be improved (Figure 3). 51 Although PVDF-based materials are the best the piezoelectric properties among piezoelectric polymers, their piezoelectric constants are still small compared to piezoelectric ceramics. In recent years, improving the piezoelectric properties of PVDF has become the focus.…”

Advanced Fiber Materials for Wearable Electronics

“…Besides conductive fibers, piezoelectric fibers are also very important for the construction of textile-based wearable electronics. These fibers are capable of generating electricity and thus, their applications are mainly in the flexible nanogenerator (FNG) devices [136]. Nanogenerators with piezoelectric effect provide the ability to convert the stress inside the material into electricity, while textiles endow the fiber-enabled wearable electronic with versatile flexible design carrier and extensive wearable application platform for their development [137].…”

Advances in Wearable Piezoelectric Sensors for Hazardous Workplace Environments

“…Incorporation of fillers or posttreatment technique such as thermal drawing and electrical polarization can be used to increase the electroactive phase fraction (𝛽-phase formation) in piezoelectric filaments. [151] Several characterization techniques are employed to measure the crystallinity of melt spun fibers including X-ray diffraction, wide-angle and small-angle X-ray scattering, and IR spectroscopy. The disadvantage of these studies is crystallinity evaluation after fiber formation, therefore needs to have a technique for in situ assessment along the process.…”