Reduced graphene oxide/mesoporous ZnO NSs hybrid fibers for flexible, stretchable, twisted and wearable NO2 e-textile gas sensor.

E-textiles are gaining growing popularity recently due to low cost, light weight and conformable compatibility with clothes in wearable and portable smart electronics. Here, an easy-handing, low cost and scalable fabricating strategy is reported to fabricate conductive, highly flexible and mechanically stretchable/twisted fiber gas sensor with great wearability and knittability. The proposed gas sensor is built using commercially available cotton/elastic threads as flexible/stretchable templates and reduced graphene oxide/mesoporous zinc oxide nanosheets as sensing layers to form conducting fibers. The as-prepared fiber demonstrates sensitive sensing response, excellent long-term stability (84 days), low theoretical detection limit (43.5 ppb NO2), great mechanical deformation tolerance (3000 bending cycles, 1000 twisting cycles and 65% strain strength) and washing durability in room-temperature gas detection. More significantly, scalable wearable characteristics including repairability, reliability, stability and practicability have been efficiently improved, which are achieved by knotting the fractured fibers, incorporating multiple sensors in series/parallel and weaving multi-sensor array networks integrated into clothes. The good sensing properties, superior flexibility and scalable applications of wearable fibers, may provide a broad window for widespread monitoring of numerous human activities in personal mobile electronics and human-machine interactions.