Kinetically Tuning the Structural Assembly of Silk Fibroin for Highly Piezoelectric Wearable Sensors

To overcome the challenges of extended processing and filler dependency for performance enhancement in pure silk fibroin (SF) piezoelectric devices, this study introduces a regeneration-free, integrated dissolution-spinning-crystallization strategy. This approach effectively enhances the intrinsic piezoelectric potential of SF by controlling the conformational rearrangement of its molecular chains and promoting the formation of ordered β-sheet crystal structures. Uniform nanofibers were fabricated under optimized conditions (6 wt % CaCl₂, 18 wt % SF, and 19 kV). A subsequent treatment with 90% ethanol induced a significant molecular rearrangement. This facilitated a structural transition from random coils, α-helices, and β-turns to highly ordered β-sheets, increasing the β-sheet content from ≈37.15 to ≈68.70%. This structural enhancement led to a remarkable improvement in performance: under a 10 N force at 3 Hz, the open-circuit voltage increased from 3.01 to 6.01 V, with a short-circuit current of approximately 53.6 nA. Without any functional fillers, this strategy successfully releases and significantly enhances the intrinsic piezoelectric potential of silk fibroin, offering an efficient and green pathway for next-generation wearable electronics and self-powered sensing applications.