Water-Responsive Xerogel-Based Flood Alarm Device Utilizing Smartphone Electrogenerated Chemiluminescence Imaging

The global incidence of flash floods has increased, leading to fatalities and significant economic losses. Hence, the development of cost-effective, timely, and efficient flood early warning systems holds significant economic and social value. In this work, a flash flood alarm device was fabricated that employed water-responsive xerogel as a core material and utilized smartphone electrogenerated chemiluminescence (ECL) imaging as the detecting technique. The water-responsive ECL xerogel was derived from the drying process of a conductive ECL hydrogel, where the conductive ECL hydrogel material was prepared by doping both Ru(bpy)₃Cl₂ luminophore and conductive indium tin oxide nanoparticles into the flexible hydrophilic polymer matrix via the crosslinking of poly(vinyl alcohol) with borax and sucrose. Intriguingly, the ECL xerogel exhibits a rapid response to water and displays a significantly enhanced ECL behavior in the presence of water. Moreover, one flood alarm device was fabricated by the incorporation of one serrate FTO electrode as the anode, five pieces of the ECL xerogel, a strip-type FTO electrode as the cathode, a battery group as the power supply, and a smartphone as the detection device. This flood alarm device demonstrates effective performance in water level warning functionalities even in dim or nocturnal conditions with cost-effectiveness, good sensitivity, and resolution, which are associated with the greatest risk of flooding. This work provides a flood alarm device based on an ECL xerogel utilizing smartphones as detectors, which is promising for the early warning of flood.