NEW DIRECTIONS IN FIBER OPTIC CHEMICAL SENSORS - SENSORS BASED ON POLYMER SWELLING

Fiber optics permit continuous in situ spectroscopic measurements, effectively bringing the spectrometer to the sample rather than the reverse. The scope of applications is greatly increased by coupling fiber optics to immobilized indicators which reversibly interact with analyte to produce an optically detectable product. More recently, systems have been developed for continuously supplying reagent to the tip of a fiber so that irreversible reactions may be used for steady state continuous measurements. Antibodies and enzymes have been combined with optical fibers to make sensitive and selective analytical measurements. However, these systems usually require addition of reagents or lack reversibility. To get back to the original idea of continuous, in situ measurements, the author has recently started to investigate a new type of sensor based on polymer swelling coupled to fiber optic displacement measurements. The principles of this type of sensor are described and preliminary results are presented here.