Sensing of Volatile Organic Compounds Using a Simplified Reflectometric Interference Spectroscopy Setup

We present a simplified optical sensor system using the principle of reflectometric interference spectroscopy (RIfS) for monitoring organic solvent vapors in air. The shift of the interference pattern caused by a change of the optical thickness of a sensitive layer, due to the influence of analyte, is investigated. The interference pattern is detected by only four wavelengths, in contrast to the system described formerly, which detects the same spectral range with a diode-array spectrometer. With the use of a direct light path between the light-emitting diodes (LEDs), transducer, and detector, no fiberoptic light guides are required. The advantages and requirements of the new optical and electronic setup as well as several applications in gas sensing are discussed with respect to the limits of detection for some analytes. Index Headings: Optical sensor; Reflectometric interference spectroscopy; Volatile organic compound; Polymer swelling; LED.