Ultrasound-mediated piezoelectricity enhancement in bioresorbable polymers.

Piezoelectric materials can power self-sustained medical devices, but biodegradable systems with high performance remain elusive. We introduce a high-frequency ultrasound treatment strategy that enhances the piezoelectricity of poly-L-lactide (PLLA) via standing-wave-induced crystallization and ferroelectric electret formation. Ultrasound at 1.2 MHz promotes β-form crystal alignment, increasing the piezoelectric coefficient (d 33 ) to 10.8 pC/N, approaching that of non-degradable PVDF. The ultrasound-treated PLLA (US-PLLA) retains full biodegradability and biocompatibility, safely degrading in vivo without organ toxicity. Functionally, US-PLLA enables real-time biosignal monitoring and promotes cardiac recovery after myocardial infarction in rats. This work establishes ultrasound-mediated crystallization as a general route to high-performance biodegradable piezoelectric polymers for transient biomedical systems.