Highly sensitive ethanol vapour measurements using a fibre optic sensor coated with metal organic framework ZIF-8

An optical fibre long period grating (LPG) based volatile organic compound (VOC) sensor coated with ZIF-8, a material from the zeolite imidazolate framework (ZIF) family, functional coating is presented. ZIF-8 film was deposited onto the surface of the LPG using an in-situ crystallization technique. A concentration specific response to ethanol was obtained over the range from 62 to 666 ppm. A novel approach for the data analysis based on the measurement of the bandwidth of the U-shaped attenuation band of the LPG is introduced. The sensor shows a sensitivity of 0.018±0.0015 nm/ppm and limit of detection (LOD) of 5.56 ppm for ethanol vapour in air.