A sandwich-like flexible nanofiber device boosts moisture induced electricity generation for power supply and multiple sensing applications

Moisture-electricity generators (MEGs) are emerging as an attractive sustainable power supply due to their clean energy harvesting and conversion. However, there still remain some challenges in the development of high-performance and practical MEGs. Herein, we develop a novel sulfonate-polyaniline-bifunctionalized lignin (SAlignin), which can be incorporated into additive polyacrylonitrile for engineering electrospun nanofiber membrane (BioMem) to improve moisture power generation. To achieve maximal electric conversion efficiency, a flexible sandwich-like MEG (fMEG) consisting of an outer bilayer electrode of carbonized BioMem and an inner hygroscopic layer of as-spun BioMem is constructed. The unique structures and compositions endow fMEG with optimal ion diffusion, streaming tendency and surface potential for moisture electric generation. Importantly, phase-field simulation reveals that the interpenetrating network of SAlignin and polyacrylonitrile has good moisture absorption capacity and electricity generation, thereby boosting electric outputs. We identify that fMEG exhibits SAlignin-dose dependent increase in power conversion efficiency, and can generate a stable voltage of 0.28 V and current of 125 nA/cm2. In addition, electric output can be further improved by assembling multiple fMEG units in series or parallel, which is sufficient to power up electronic devices. More excitingly, fMEG can sensitively detect humid wind, and especially harvest the energy from human breath for respiration monitoring. Particularly, fMEG exhibits the potential of real-time monitoring of different human motions, including finger movements, sound waves and neck pulses. Therefore, our study provides new insights for advancing MEGs and related applications.