Optical fiber acetone sensor functionalized with a zinc-based metal–organic framework

A reflective optical fiber sensor coated with zeolitic imidazolate framework-8/nitrogen-doped porous carbon (ZIF-8/NPC) is developed in this study for the online, rapid, and selective detection of acetone vapor. The sensor includes an optical fiber and an acetone-sensitive unit. The sensing unit is constructed on a polymethyl methacrylate substrate with a linear groove, where inner groove walls are coated with a Ag film and ZIF-8/NPC composite layer, which forms a light transmission channel. A theoretical sensing model is established on the principle that acetone absorption increases the refractive index of the sensing film, and this leads to enhanced light absorption at 256 nm. Effects of the ZIF-8/NPC composition, coating thickness, and number of light reflections on sensor performance are investigated systematically. The sensor achieved selective and accurate acetone detection under optimized conditions of ZIF-8/NPC coating thickness of 20 μm, three reflection cycles within the sensing channel, ambient temperature of 20–30 °C, and relative humidity of 50–60 %. This sensor exhibited a sensitivity, detection limit, response time, and maximum relative error of 0.000544 AU/ppm, 5.5 ppm, 250 s, and 2.6 %, respectively. The sensor demonstrated high selectivity toward acetone and long-term stability. This study provides a new approach for in situ and rapid acetone monitoring in environmental applications and contributes to advancing optical fiber sensing technology.