The Tribond Bridged Bipyridine Complex-based In-fiber Interferometric Sensor design for Cu2+ Detection

We report a real-time, lightweight sensor based on in-fiber MZ interferometer coating bipyridine complex L[4-methyl-2, 6-bis(pyridine-3-ylethynyl)aniline](L-ligand) in situ determination of free copper ion at micromolar levels. The sensor is made by fusing a section of thin-core fiber(TCF) in the middle of singlemode fiber(SMF). The L-ligand material is attached to the sensing surface of thin-core fiber to bind free copper ions in liquid environment with high affinity and selectivity. Investigation was carried out that the performance of the sensor is significantly improved with different length. The sensitivity of Cu2+ detection can reach 0.0573 nm/μM (nanometer per micromolar) in linear range of 0μM~25μM and the detection limit is 0.8726μM. This is significantly lower than the allowable level of drinking water.