Smartphone compatible on-site fluorescence analyzer for spilled crude oil based on CMOS image sensor

Oil spills, both in the ocean and inland waters, have negative effects such as mass mortality and habitat destruction. In this study, we develop a spilled oil point-of-testing device (SOPD), a field measurement system for immediate on-site fluorescence monitoring of oil concentrations. Photodetectors, such as photodiodes and photo multiplier tubes, which are commonly used in existing instrumentation, have inherent limitations because they are capable of only single-pixel detection. However, SOPD can cope with environmental noise caused by dust, dirt, and impurities, by adopting a multi-mega pixel complementary metal-oxide semiconductor image sensor as a detector. Furthermore, the manufacturing cost is remarkably reduced by a simple optical configuration using only two light-emitting diode light sources, five optical lenses, and a CMOS sensor. SOPD can quantitatively analyze fluorescence intensities at both low (0–1 ppm) and high (1–800 ppm) concentrations in marine and inland environments, respectively. The performance of the equipment reported in this paper was demonstrated by measuring the linear measurement range and the limit of detection using five different kinds of crude oil. A correlation analysis of crude oil samples having different collection dates was also completed. In addition, SOPD has been developed as a remote system that can be operated and analyzed on a smartphone, thereby enhancing user convenience, reducing analysis time, and simplifying device.