3D self-assembled crumpled porous carbon microcapsules as a versatile platform for self-sustainable multi-modal wearable electronics

The rising Internet-of-Things industry has generated considerable interest in self-sustainable multimodal flexible wearable electronics. However, it remains challenging to fabricate various functional modules for self-sustainable flexible electronics using a single process and material. In this study, monodispersed lignin sulfonate-reduced graphene oxide nanosheets were transformed into 3D self-assembled porous carbon microcapsules (LRCMCs) through ethanol-assisted spray-drying and carbonization. Due to their well-developed porous structure, good conductivity and dispersibility in specific solvents, the resulting LRCMCs could serve as a versatile platform for fabricating various patterned flexible sensors and supercapacitors on flexible Ecoflex substrates through simple solvent drop-casting and transfer printing technology. Results indicated that the sensitivity and detection range of LRCMCs-based flexible strain sensors could be effectively tailored through patterned designs. Therein, the straight-line patterned flexible sensor exhibited an extremely high gauge factor (GF) of ∼219, wide detection range (0–225 %), excellent mechanical durability, and cyclic stability (3000 cycles) for human physiological and physical activities detection. Moreover, a flexible LRCMCs-based humidity sensor was constructed, which could quantitatively measure ambient humidity and monitor human perspiration behavior. For achieving the self-sustainability of multimodal flexible electronics, a flexible supercapacitor was also fabricated using LRCMCs as electrode materials to provide sufficient energy density and driving voltage.