Novel side-polished balloon shaped heterocore structured plastic optical fibre ethanol sensor

A unique side-polished balloon shaped heterocore structure plastic optical fibre (POF) sensor for real-time measurement of very low to high ethanol concentration in water is reported. The sensor is designed as a large core-small core-large core heterocore structure where small core fibre (SCF) acts as a sensing region, whereas large core fibre (LCFs) are used as input and output light waveguide s as well as to introduce the light leakage in the cladding of SCF at the heterocore structure’s input interface and hence generate the significant evanescent field. The principle of operation of the sensor is based on evanescent field interaction at the interface of modif ied SCF and the liquid boundary. The sensor is characterized for ethanol-water solutions in the ethanol concentration ranges of 20 %v/v to 80 %v/v, 1 %v/v to 10 %v/v, and 0.1 %v/v to 1 %v/v, demonstrating a maximum sensitivity of 54673 %/RIU. The experimentally evaluated high sensitivity of this sensor design for real-time measurement of ethanol concentration in water at different ranges makes it a potential candidate for implementation in the industry as a low-cost and real-time solution for ethanol sensing as well as other RI sensing applications.