Topologically Structured PLLA Fibers With Stress Concentration Effects for Health Monitoring.

The development of flexible electronic devices necessitates materials with high piezoelectric performance. Poly(L-lactic acid) (PLLA) nanofiber-based piezoelectric membranes hold promise for self-powered health monitoring and tissue repair, yet their intrinsic piezoelectric performance remains insufficient for practical applications. Here, we develop a multi-path strategy to enhance the piezoelectric properties through crystallography and hierarchical design of PLLA fibers. We also demonstrate that incorporating high-aspect-ratio needle-like hydroxyapatite (HAp) into PLLA optimizes crystallinity and enhances piezoelectric output. Building upon this, we construct PLLA-HAp/PLLA composite fiber membranes with topological structures to further amplify the piezoelectric effect. Notably, low-concentration HAp dispersed within random PLLA fibers induces stress concentration at the interface with aligned PLLA fibers, resulting in satisfactory piezoelectric performance. In the impact mode and bending mode, the piezoelectric output is approximately 6 and 14 times that of pure PLLA fiber, respectively. The optimized fiber membranes demonstrated excellent potential for monitoring human physiological activities, as validated by subsequent experiments that successfully recorded porcine joint movements and heart rates. This piezoelectric enhancement strategy offers a new approach for next-generation high-performance piezoelectric devices, with broad applicability in health monitoring and tissue engineering.