Flexible and weavable 3D porous graphene/PPy/lignocellulose-based versatile fibrous wearables for thermal management and strain sensing

Fibrous wearable electronics have attracted extensive attention owing to their lightness and flexibility. However, they face challenges to work synergically with conductive components when stable performance and multifunction are required simultaneously. Here, plant-extracted 3D porous Juncus effusus (JE) fiber decorated with conductive graphene/polypyrrole (G-PPy) yields flexible smart fibers (G-PPy-JE) with integration of Joule heating and strain sensing properties. G-PPy-JE fibers were prepared by hierarchically anchoring the graphene sheets and PPy to 3D JE microfibrils via a facile dip coating and in-situ polymerization method. Synergistic effects in the hybrid architecture contribute to a highest conductivity of G-PPy-JE (96.85 S m⁻¹) compared to pristine JE, G-JE, and PPy-JE. On the one hand, G-PPy-JE fibers showed a great electric-thermal property, which achieved a temperature of 147 °C at 10 V within 10 s. The good Joule heating performance maintained when weaving these fibers into fabrics as thermal therapy clothing. On the other hand, G-PPy-JE fibers after encapsulation can serve as a strain sensor with a high sensitivity (GF of 7.36–11.36), great stability (10–100 %), and good durability over 500 cycles. The strain sensor also reflected capabilities to detect a full range of human motions. This work paves a way for manufacturing cost-effective, green, and versatile fibrous electronics for promising wearable application.