Intrinsic fiber optic chemical sensor for the detection of dimethyl methylphosphonate

We report the early stage development of an intrinsic fiber optic sensor to detect the presence of nerve agent sarin simulant dimethyl methylphosphonate (DMMP). The sensor design is based on the modified cladding or coating approach. Conducting polymer polypyrrole is the chemo-optic transducer, i.e., is used as a modified cladding material. Sensitivity to approximately 134 ppm of DMMP is demonstrated in the developed sensor, with a sensor response of 20 mV and a response time of 2 sec. Morphology characterization of the polypyrrole is performed by scanning electron microscopy. Selectivity study of the developed sensor is presented by exposing the sensing element to other gases like acetone and ammonia. Influence of temperature and humidity on the developed sensor is investigated, along with ambient aging of polypyrrole films. (C) 2004 Society of Photo-Optical Instrumentation Engineers.