A Biodegradable and Tough Piezoelectric Silk Fibroin Fiber

Biodegradable piezoelectric implants are optimal platforms for transient biosensing and therapeutics. However, limited piezoelectric properties and toughness impede the deployment of biodegradable piezoelectric implants in dynamic tissues and organs. In this study, we have developed silk fibroin (SF) fibers with high piezoelectricity and toughness via a microfluidic spinning method and post‐treatment via dynamic salting‐out (DSO). The optimized SF‐DSO fibers exhibited remarkable mechanical properties (fracture strain: 45.58%, toughness: 115.03 MJ/m 3 ) and enhanced piezoelectric performance ( d 33, eff = 26.51 pC/N). Fourier‐transform infrared spectroscopy (FTIR) and two‐dimensional wide‐angle X‐ray scattering (2D‐WAXS) analyses revealed increased β‐sheet content and molecular alignment, correlating with improved properties. The fibers also showed excellent cytocompatibility and biodegradability, confirmed by in vitro and in vivo evaluations. Piezoelectric films based on SF‐DSO fibers provided stable electrical outputs and were successfully used for in vivo applications, including respiratory monitoring, muscle motion detection, and ultrasound‐driven energy harvesting in rats. The regenerated SF‐DSO fibers prepared in this study offer a promising option for next‐generation biodegradable piezoelectric implants.