Refractive index measurements of ethanol-water binary liquid solutions using a graded-index fiber tip sensor

Abstract

The refractometric analysis of ethanol-water mixtures is hampered because this type of binary solution does not present a linear behaviour. In this work it is proposed a multimode Graded-Index Fiber (GIF) tip sensor for the measurement of ethanol in binary liquid solutions of ethanol-water. The probe is fabricated by fusion-splicing a 500 µm GIF to a Single Mode Fiber (SMF) and it operates as a refractometric sensor in reflection. Samples of ethanol-water mixtures were measured at different temperatures (20°C to 60°C) to evaluate the probe’s capability to detect variations in ethanol refractive index. The samples have different % (v/v) of ethanol, in a range between 0% and 100%.