A reusable optical fiber sensor for ethanol gas detection with a large concentration range

Ethanol is an important material in for chemical, pharmaceutical or food industry. But ethanol gas in the air induces health danger and explosion risk. Therefore, the concentration of ethanol gas must be monitored. In this paper, an optical fiber device for ethanol gas detection is demonstrated. Glycerol aqueous solution is taken as the ethanol absorbent, a Teflon capillary is used as the gas permeable cell and a surface plasmon resonance (SPR) fiber sensor is employed as the receiver. When ethanol gas permeates into the capillary and be absorbed by the absorbent, the refractive index of the absorbent is modulated and then detected by the SPR sensor. With this principle, sensing devices were fabricated and tested. Within the range of 0–7534 ppm, the limit of detection (LOD) is obtained as 38.31 ppm. In cycle test, the excellent reusability, repeatability and durability are testified. In addition, with the large detectable range and low cost, the proposed device may realize wide applications in industrial process.