Buoyant fluorescent particles as a novel sensing technology for field observations of water flows

In this paper, we investigate the feasibility of off-the-shelf buoyant fluorescent microspheres as particle tracers in turbid water flows. Microspheres' fluorescence intensity is experimentally measured and detected in static aqueous suspensions of increasing concentrations of clay to simulate typical conditions of natural drainage networks. We conduct experiments by using photoconductive cells and image-based sensing methods. Results obtained with both approaches exhibit comparable trends and show that the considered particles are detectable in critically turbid water flows. Further information on the performance and integration of such microspheres in low-cost measurement instrumentations for field observations is obtained through experiments on a custom built water channel. Findings from this study show that the proposed technology may serve as a minimally invasive sensing system for hazardous events, such as pollutant diffusion in natural streams and flash flooding due to extreme rainfall.