Distributed Optical Fiber Sensor for Long-term Monitoring of Groundwater Trichloroethylene Levels

There is a current need for sensor technologies that can be used for the long-term monitoring of groundwater, specifically for chlorinated hydrocarbons, such as trichloroethylene (TCE). Sensors should meet required pollutant detection levels and be small enough, yet robust, and be capable of being deployed at a reasonable cost. The sensor formant should include flux meters and piezometers to characterize change over small vertical and horizontal scales. Intelligent Optical Systems, Inc. (IOS) proposes a distributed fiber optic TCE sensor employing a novel indicator chemistry that will help to overcome the drawbacks historically associated with the Fujiwara indicator. IOS’ new approach to TCE monitoring is based on the use of a new colorimetric indicator that has excellent miscibility with IOS’ proprietary, highly permeable, ultraviolet light curable, optical cladding polymers. The resultant fiber sensor coating, which is highly sensitive to low levels of TCE in water, undergoes color changes from clear (when unexposed) to deep red (when exposed) to TCE. This distributed optical fiber detection approach meets the required monitoring parameter, and will offer high sensitivity and the simultaneous monitoring of multiple locations. This study will prove the feasibility of using this newly discovered TCE indication in an optical fiber cladding sensor to detect low levels of TCE. The successful results will lead to the development of cost-effective, robust, sensitive, distributed TCE sensors for the remote, long-term monitoring of groundwater.