UiO-66 metal-organic framework integrated Michelson interferometer for fluoride-ion detection

In this work, a novel Michelson interferometer (MI) based on the core-offset splicing between the single-mode fiber (SMF) and thin-core fiber (TCF) is proposed and experimentally demonstrated. By using the layer-by-layer self-assembly method, a novel metal-organic framework UiO-66 film is coated on the TCF surface. Then, the MI for fluoride-ion detection is obtained. The adsorption of fluoride ions by the sensing film induces the change in the effective refractive index (RI) of the coated cladding, which results in the regular redshifts of the interference dip. Different fluoride-ion concentrations can be obtained in real-time by monitoring the dip wavelength shifts. The proposed sensor exhibits an excellent linear response in the fluoride-ion concentration range up to 0.1 ppb, a high sensitivity of 612 pm/ppb and a fast response time of 10 s.