All-Fiber Optic Chemical Sensors for Public Safety Monitoring
The leakage of toxic or flammable chemical substances that might affect or endanger public safety has always attracted the attention of the researchers to develop a chemical sensor that could prevent any life-threatening incidents. Due to its robust features, hard polymer clad fiber (HPCF) was used in this experiment to develop an all-fiber optical chemical sensor. The outer hard polymer clad was removed by using mechanical method to expose the inner core. The exposure lets contact between the leaked chemical and the core, both with different refractive indices (RI). The change in signal property of the passing light wave occurs at this point and hence can be detected using optical time-domain reflectometer (OTDR). In this way, HPCF was transformed into a fiber optic chemical sensor. OTDR was used as a sensing system that allowed the sensor to detect and localize the leakage of chemical substances in real-time, by measuring the light loss in backscattering light (signal) that was caused due to extraction of chemical on fiber cladding. This light loss is based on leaky wave mode principle. The reliability of the sensor was tested with Benzene, Toluene, Pyridine, Dimethylsulphoxide and several other toxic chemicals. The results showed that the sensor was able to detect the chemicals (in liquid state) and localize the event positioning. With the promising results, the sensor will be further tested with different types of chemicals to optimize the fiber chemical sensing system.
Joong Hee Lee
J. R. Lee et al., "All-Fiber Optic Chemical Sensors for Public Safety Monitoring", Advanced Materials Research, Vols. 123-125, pp. 855-858, 2010