A. Talukder, S. Mesihovic, S. Sharma
University of Georgia,
United States
Keywords: energy harvesting, piezoelectric, nanoparticles
Summary:
The integration of flexible, wearable electronics with sustainable power sources has become an emerging priority in next-generation wearable textiles. Conventional batteries are bulky, rigid, and environmentally unsustainable, thereby limiting the long-term deployment and comfort of wearable textiles. To overcome these challenges, there is a growing demand for efficient energy-harvesting systems that can continuously convert mechanical motion into usable electrical energy. In this study, we report the fabrication and characterization of nanoparticle-modified stainless steel thread–based piezoelectric coaxial yarn nanogenerators, designed to function as scalable and flexible energy harvesters for wearable electronics. The nanogenerators were fabricated using a solution coating method, a process offering high throughput, low processing complexity, and potential scalability from laboratory to industrial production. The core structure consists of a stainless steel thread serving as the inner electrode, providing mechanical robustness, electrical conductivity, and compatibility with conventional textile manufacturing. The coating layer comprises a poly(vinylidene fluoride) (PVDF)–TiZnCeO nanocomposite, which was uniformly deposited around the metallic core to form a coaxial structure. PVDF was selected because it offers remarkable mechanical flexibility, biocompatibility, and high piezoelectric coefficients, which make it ideal for practitioners using nanogenerators to convert ambient piezoelectric energy into electrical power. PVDF, a semicrystalline polymer, has five different crystalline phases α, β, γ, δ, and ε, where the β and γ phases are the polar phases of PVDF; however, the β phase is more important than the other phases due to its better piezoelectric properties. Researchers focus on enhancing the piezoelectric properties and increasing the β-phase content in PVDF by introducing different nucleating fillers, including nanoparticles, nanofillers, and nanowires [1]. Researchers in various studies relied on metallic oxides, particularly on transition metals such as titanium and zinc, which can enhance the specific β-phase content by introducing electrostatic interactions and mechanical stress, encouraging dipole alignment within the PVDF polymer matrix [2], [3]. Also, cerium-containing composites have been found to influence the polarization of the PVDF polymer, further aiding in the transition from α to β [4]. These synergistic effects substantially increased the piezoelectric response of the resulting nanocomposite layer. Morphological and structural analyses via scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) confirmed uniform coaxial coating and a high fraction of β-phase content. The resulting coaxial yarns retained the mechanical flexibility, tensile strength, and surface texture of standard textile fibers, enabling seamless integration into fabrics without compromising comfort or durability. Under various mechanical deformations—including bending, twisting, compression, and stretching—the nanogenerators generated measurable open-circuit voltages and short-circuit currents, confirming their functionality as self-powered generators. The output performance demonstrated stability across repeated cycles, indicating excellent fatigue resistance and material adhesion at the fiber–matrix interface. In summary, the proposed PVDF/TiZnCeO-coated stainless steel coaxial yarn nanogenerators represent a scalable, robust, and eco-efficient route toward sustainable energy solutions for wearable systems. This work bridges the gap between laboratory-scale nanogenerator research and industrial-level textile manufacturing, paving the way for next-generation self-powered wearable electronics in healthcare, sports monitoring, and human–machine interface applications.