Fluorinated Bismaleimide Composites with Enhanced Piezoelectric Characteristics for Motion Monitoring

The design and development of a function–structure integrated composite for harsh environments is in high demand. This study develops a flexible piezoelectric sensor (FBMI-BN) based on fluorinated bismaleimide (FBMI) resin, boron nitride (BN) particles, and a glass fiber mat to address the limitations of conventional piezoelectric sensors in extreme environments (high temperature, humidity, strong acids/bases, etc.). Results demonstrate that BN incorporation significantly enhances the mechanical properties, thermal stability (5% decomposition temperature, 410 °C; glass transition temperature, 270 °C), dielectric performance (dielectric constant, 3.2–4.8, dielectric loss, 0.01–0.06), thermal conductivity, and piezoelectricity. The composite films exhibit storage moduli of 6–13 GPa, tensile strengths of 13–25 MPa, and Young’s moduli of 500–2500 MPa. The optimized FBMI-BN10% sensor achieves exceptional piezoelectric outputs (20 V and 850 nA) with rapid response/recovery times (17/23 ms), high sensitivity (1.17 V·kPa–1), and remarkable durability (>12000 cycles). Practical applications in wearable electronics and motion monitoring are demonstrated through the real-time detection of human movements and badminton stroke dynamics. This work provides a robust strategy for designing high-performance sensors operable under harsh conditions.