Stereocomplexation-Enhanced Electroactivity of Poly(lactic acid) Nanofibrous Membranes for Long-Term PM Capturing and Remote Respiratory Monitoring

Development of poly(lactic acid) (PLA) nanofibrous membranes (NFMs) holds great potential to replace the conventional nondegradable air filters, but is largely thwarted by the intrinsically low electroactivity and poor electret properties of PLA. Here, highly electroactive PLA NFMs coupling the triboelectric nanogenerator (TENG)-based recharging mechanisms are demonstrated for long-term respiratory protection from fine and ultrafine particulate matters (PM0.3 and PM2.5), as well as wireless intelligent monitoring of physiological characters. To enhance the in situ electret and self-charging mechanisms for the PLA NFMs, we proposed a stereocomplexation strategy involving direct electrospinning of PLLA/PDLA nanofibers (approaching 500 nm), conferring a remarkable promotion of electroactive phases, dielectric properties, surface potential (over 10 kV), and triboelectric output properties (nearly 20 V at the humanoid breathing conditions). Benefiting from the well-tailored morphology and self-charging features, the PLA NFMs exhibited high surface potential (180 V) and excellent air filtration performance (96.32% for PM2.5 and 92.09% for PM0.3) while providing a desirable air resistance (only similar to 200 Pa even at 85 L/min), far surpassing those of the pristine PLLA counterpart (60 V, 72.92%, and 281 Pa, respectively). This was accompanied by high-sensitivity in vivo monitoring of cardiorespiratory characters such as coughing and breathing, essentially arising from the respiration-triggered distinct TENG mechanisms. Featuring long-term efficient filtration and noninvasive monitoring, our biodegradable electroactive NFMs are appealing for respiratory healthcare and real-time monitoring.