PVDF系圧電複合材料におけるβ相エンジニアリングの最近の進歩：圧電性とウェアラブル応用への強化

Piezoelectric materials, enabling mutual conversion between mechanical and electrical energy, are foundational to numerous sensing and actuation technologies. Poly(vinylidene fluoride) (PVDF) and its copolymers are among the most promising polymer-based piezoelectric materials owing to their flexibility and processability. Their piezoelectric response originates primarily from the polar β phase, which exhibits the highest dipole alignment among all crystalline phases. However, pristine PVDF typically crystallizes in the nonpolar α phase, resulting in limited piezoelectric activity. Consequently, programming the β phase has emerged as a key strategy to enhance the piezoelectric performance of PVDF-based composites. In this review, we comprehensively summarize β-phase regulation strategies and their impact on device applications. We first analyze recent advances in β-phase programming of PVDF-based composites, with emphasis on in situ electrical poling, mechanical processing, and filler doping. The underlying mechanisms, structure-property relationships, and representative studies are also systematically discussed. Furthermore, we highlight the applications of high-performance PVDF-based composites in health monitoring and energy harvesting. Finally, the current challenges and future opportunities are outlined to provide insights into the development of next-generation PVDF-based piezoelectric systems.