Dual-mode core–shell structured early fire warning sensing fiber with selective CO and temperature detection

Early fire warning represents an effective mean in the face of fire that can remind people in timely manner to adopt effective countermeasures before the occurrence of fire. Despite the encouraging progress of current early fire-warning sensors, a more sensitive monitoring of early fires in multiple aspects remains challenge. Herein, a dual-mode core-sheath structured SnO 2 /MoS 2 @MXene@ANFs (SMA) early fire warning sensor fiber was prepared by coaxial wet spinning technology. The core-layer of SMA fiber comprised the thermoelectric material Ti 3 C 2 T X MXene, whereas the shell-layer comprised the gas-sensitive SnO 2 /MoS 2 and silver nanowires (Ag NWs) along with aramid nanofibers (ANFs). The robust and flame-retardant ANFs served as protective shell, safeguarding the stability and flexibility of the temperature and gas sensing functions within the fiber. Based on the thermoelectric performance of MXene, there is a linear relationship between the output voltage and temperature difference of SMA fiber, which can achieve wide range of temperature sensing from 50 to 300 ℃ and accurately identify abnormal temperature increases in the environment. Simultaneously, The bridging effect between one-dimensional Ag NWs and SnO 2 /MoS 2 enhances the sensing capability of fiber for CO (R 0 /R = 1.43@100 ppm). In addition, an early fire warning system based on SMA fiber has been established, which can sensitively detect the flames (≤4 s). This system can also be used for monitoring CO gas in fire environments, guiding firefighters’ rescue actions, expanding the application scope of early fire warning sensors in the past, and opening up new directions for the development of intelligent early fire sensors in the future.