Highly flexible all-inorganic nanofiber networks with stress-accommodating microstructure for light-activated wearable chemiresistive sensor

Inorganic semiconductor chemiresistors have been the mainstream of well-explored gas sensing technology. However, the intrinsic fragile and rigid nature seriously impedes their future application in the thriving wearable sensing devices. Herein, we demonstrate a flexible all-inorganic semiconductor-based chemiresistive sensor through in-situ anchoring nanosheets-assembled SnO2/SnS2 sensing layer on flexible yttria-stabilized zirconia (YSZ) ceramic nanofiber networks. It is revealed that the flexible YSZ ceramic substrate possesses low section modulus in bending and good toughness that is mainly derived from its unique nanofiber structure (300 nm in diameter) and ultrafine grain size (16 nm). It is first demonstrated that nanosheets-assembled sensing layer characterized by abundant void spaces plays a pivotal role in affecting the flexibility of inorganic nanofiber networks. The void spaces between SnO2/SnS2 nanosheets, acting as stress-accommodating microstructures, could effectively releasing stress concentration, enabling abnormal mechanical flexibility of inorganic YSZ/SnO2/SnS2 network. In addition, to achieve more compatibility with wearable application and realize room-temperature gas sensing function, visible light rather than traditional high heat is employed as excitation source to activate the flexible YSZ/SnO2/SnS2 chemiresistor. This work shows the possibility of inorganic semiconductor chemiresistor for application in wearable sensing device and offers a valuable guidance for constructing flexible room-temperature inorganic chemiresistor.