Bio-based chitosan-based film as a bifunctional fire-warning and humidity sensor.

Early fire detection is an efficient method to mitigate disastrous fire loss. However, developing smart low-temperature fire-warning sensors that better diminish fire hazards, especially those caused by household appliances, is still challenging. Herein, a salts-modified chitosan (salts-modified CS) based sensor with integrated fire-warning and humidity-monitoring capability is proposed using an easy assembling method. This sensor can respond to temperatures as low as 50 °C and a flame within 2 s quickly and detect relative humidity (RH) range above 50 % at 50 °C and 75 °C sensitively. This system can be reusable for multiple ignitions and works in high-humidity environments (>50 %). Furthermore, the comparison between different salts-modified CS films is carried out to elucidate the mechanism of the formation of electric current under the joint driven by temperature and humidity. Moreover, real-time temperature and RH monitoring can be achieved with a wireless transmission section. This design shows a promising approach for multifunctional CS-based sensors and paves a path to developing a new generation of smart fire-warning detectors.

Recent Advances on Early-Stage Fire-Warning Systems: Mechanism, Performance, and Perspective.

Early-stage fire-warning systems (EFWSs) have attracted significant attention owing to their superiority in detecting fire situations occurring in the pre-combustion process. Substantial progress on EFWSs has been achieved recently, and they have presented a considerable possibility for more evacuation time to control constant unintentional fire hazards in our daily life. This review mainly makes a comprehensive summary of the current EFWSs, including the working mechanisms and their performance. According to the different working mechanisms, fire alarms can be classified into graphene oxide-based fire alarms, semiconductor-based fire alarms, thermoelectric-based fire alarms, and fire alarms on other working mechanisms. Finally, the challenge and prospect for EFWSs are briefly provided by comparing the art of state of fire alarms. This work can propose a more comprehensive understanding of EFWSs and a guideline for the cutting-edge development direction of EFWSs for readers.