Extreme Orientation of Stereocomplexed Poly(lactic acid) Induced Ultrafine Electroactive Nanofibers for Respiratory Healthcare and Intelligent Diagnosis

Biodegradable and renewable poly(lactic acid) (PLA) fibrous membranes have emerged as a promising approach to replace traditional polymeric air filters, but are still challenged by relatively low electroactivity and poor electret properties. Herein, we disclose an effective electrospinning strategy to substantially promote the electroactivity by extreme orientation of stereocomplexed PLA (OSC-PLA), conferring significant alignment and refinement of the electrospun nanofibers (diameter of ∼370 nm), as well as facilitate the formation of electroactive phases (i.e., β-phase, electrospun phase, and stereocomplex crystals). Benefiting from the well-tailored morphology and remarkable electroactivity, the OSC-PLA nanofibrous membranes (NFMs) were characterized by largely improved dielectric properties, surface potential (over 3.64 kV), and PM0.3 filtration properties (93.33% at 85 L/min) compared to the pure PLLA membrane (2.01 kV and 80.21%). It enabled the assembly of triboelectric nanogenerator (TENG) air filters using the OSC-PLA NFMs as the active layer, yielding excellent charge regeneration mechanisms and an output current of nearly 80 nA, as driven by respiratory vibrations at 85 L/min, thus permitting high humidity resistance, as exemplified by a PM0.3 removal efficiency of 95.02% at a RH of 90%. Moreover, deep machine learning and man–machine interaction were integrated with the OSC-PLA-based TENGs, demonstrating long-term monitoring and a high-precision diagnosis (accuracy of 96.88%) of various respiratory patterns. The proposed ecofriendly and electroactive ultrafine PLA nanofibers are highly appealing for sustained respiratory healthcare and self-powered intelligent diagnosis.