Detection of Solvents using a Distributed Fibre Optic Sensor

Introduction: In this Letter an optical fibre sensor capable of making fully distributed measurements of a wide range of solvents is identified. Microbending principles have been used to develop the sensor such that it responds on contact with liquid solvents, typically within 30 seconds of exposure. The sensor incorporates a swelling polymer and optical fibre components that are readily available in the optical communications industry. A conventional optical time domain reflectometry (OTDR) technique is utilised for sensor interrogation and location of multiple spill events over a range of 20km. The sensor uses a low-power laser source to perform the sensing function and due to its optical nature is intrinsically safe. The operational characteristics of the sensor and the underlying technology utilised in its operation are described. The swelling characteristics of the polymer material in a range of solvents and experimental test results of prototype sensors are presented.