Preparation of Metal Core Piezoelectric Fiber Based on a Mold-Assisted Wet Process

Metal core piezoelectric fiber (MPF) is gaining attention for their potential applications in smart wearables and fault detection due to their excellent dynamic responsiveness. Traditional manufacturing methods, however, are hindered by inefficiencies, environmental concerns, and inconsistent quality, limiting the large-scale production and application. This research presents a novel continuous fabrication method for MPF using enamel-coated wire molds. By optimizing the incorporation of lithium chloride (LiCl), we achieve a phase transition to the β-phase, significantly enhancing their piezoelectric properties. Utilizing a recrystallization process, a homogeneous P-(VDF-TrFE) crystalline layer forms rapidly on the fiber surface, while a combination of spray coating and thermal shrinkage ensures uniform encapsulation of the external electrode layer. Our experimental results confirm that this method produces MPF with well-defined coaxial structures and optimized surface morphologies, making the process cost-effective and environmentally friendly. The resulting fiber demonstrates strong responsiveness and linearity under external stresses, suitable for full-field sensing applications. Additionally, we integrate these MPF into a cycloidal reducer prototype, enabling real-time monitoring of speed and operational stability, thus overcoming limitations of conventional detection systems. This research highlights the significant potential of MPF in developing advanced, high-precision reduction systems.