A low-cost fluorometer incorporating an array of four photodiode detectors with different colors of cellophane film filters detects and distinguishes among different types of crude and refined oil.

Researchers from the University of Vigo, Spain, designed the sensor 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.

Emulsified oil located in an intertidal area on Grand Isle, La Credit: NOAA's Office of Response and Restoration.Oil emits a unique fluorescence spectrum as it absorbs UV light. This spectrum is used by the device as a sort of a fingerprint to identify the oil type by comparing measured fluorescence with information in a database.

The instrument is based on the measurement of induced fluorescence using 280 and 390 nm LEDs as excitation sources. Inexpensive UV LEDs serve as light sources, and a commercial radio module sends data and receives configuration commands.

Laboratory measurements were conducted on three types of crude oil provided by an oil company and two types of refined oil. Thin films of each type of oil were generated on a water surface to simulate oil spill conditions. A specific fingerprint produced for each oil type tested allowed the researchers to identify the different types of oil.

The next goal is to construct a solar-powered prototype that could be placed in a buoy, for example, and left in a lake or ocean for months. The prototype, including the buoy, will have a height and diameter of about 30 cm and will have the capability to send measurements to a remote user via a radio module or even by satellite modem.