Self-Powered Fire Alarm System with Layer-by-layer Graphene Oxide/Chitosan Nanocoating of Flame-Retardant Nanofilms

This study develops a self-powered fire alarm system that utilizes a sandwich-like self-powered fire sensor (SSFS) with a simple system to prevent room fires. The SSFS is small, flame-retardant, and can be easily installed on furniture or doors. The SSFS uses a nanogenerator constructed by poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) nanofibers and a flexible printed circuit board (FPCB) to produce electrical power by harvesting motion energy. This nanogenerator can fully charge capacitors in a few minutes and produces a maximum voltage output of 6.47 V. The SSFS also features two flame-retardant melamine foams (MFs) coated with graphene oxide (GO) and a chitosan multilayer nanocoating that is fabricated by layer-by-layer technology (LBL technology). While encountering a high-temperature situation, the electrical state of MFs changes from insulated to conductive, triggering the fire alarm light in about four seconds. The sandwich-like design allows the SSFS to respond to a variety of fire alarm situations, especially in the case where both the top and bottom of the fire alarm sensor are exposed to flame (bilateral fire burning). It is such an innovative research to decrease the delay time of fire-warning by using this sandwich-like design fire sensor. The nanogenerator can keep the warning working for 22 s after the initial trigger, which produces enough time to ensure people stay clear of the fire source. All in all, this study presents a novel approach to reducing the risk of building fires through a lightweight and self-powered fire alarm system that harvests motion energy using piezoelectric nanogenerators (PENGs).