A simple device composed of photodiode detectors can detect an oil spill in water and then pinpoint the type of oil present on the surface. Researchers from the University of Vigo created the device that is designed to float on water, where it could remotely monitor a small area susceptible to pollution or track the evolution of contamination at a particular location. "Fast detection of a spill is crucial for a quick antipollution response to avoid, as much as possible, the progressive mixture of the oil into the water, which would make cleaning more difficult and inefficient," said Jose R. Salgueiro, lead researcher at the University of Vigo. Researchers developed a device that uses fluorescence from oil (left) to detect its presence and identify the type of oil. The small and simple device incorporates inexpensive electronic components (right). Courtesy of Oscar Sampedro/University of Vigo. Aircraft and satellite instrumentation is often used to look for oil spills in large bodies of water. The new device is a simpler, effective means to monitor a certain area on an ongoing basis. When crude or refined oil absorbs UV light, it emits a unique fluorescence spectrum. The new device uses this fluorescence spectrum as a sort of a fingerprint to identify the oil type by comparing the measured fluorescence with information in a database. The research team used an inexpensive setup of four photodiode detectors with different colors of cellophane film filters, allowing them to record four different signals across different regions of the fluorescence spectrum. They used UV LEDs as light sources and a low-cost microcontroller often used to operate drones. The researchers tested their instrument by conducting laboratory measurements on three types of crude oil provided by an oil company and two types of refined oil; they recreated the conditions of an oil spill by generating thin films of each type of oil on a water surface. "The four signals proved to be enough to build a specific fingerprint for every oil type used in our study, letting us identify the different types of oil," Salgueiro said. "This approach dramatically reduces the cost of the instrument and simplifies contamination testing." Now that the researchers have demonstrated their device in the laboratory, they plan to construct a solar-powered prototype that could be placed in a buoy and left in a lake or off shore in the ocean for months. The prototype device, including the buoy, will have the capability to send measurements to a remote user via a radio module or satellite modem. The research was published in Applied Optics (doi.org/10.1364/AO.56.002150).