An evanescent wave enhanced C3N4-MIL-53 functionalized micro-structure polymer optical fiber sensor for highly sensitive detection of Tetracycline

Tetracycline (TC) detection is crucial for food safety, ecological balance, and human health. This study proposes an evanescent wave enhanced micro-structure polymer optical fiber (POF) sensor for highly sensitive detection of TC by employing the C 3 N 4 -MIL-53 heterostructure. The micro-structure composed of a side-polish region and micro-grooves, which can effectively enhance the intensity of POF's evanescent wave. The C 3 N 4 -MIL-53 heterostructure was fabricated and modified on the side-polish region as the sensitive film for selective adsorption and enrichment of TC molecules. This molecular adsorption process induced localized refractive index increases in the film, which subsequently led to an attenuation of the transmitted light. A theoretical model was established to illustrate the enhanced sensing principle of the micro-structure on POF and the structural parameters of the sensors are experimentally optimized. The sensor demonstrates the rapid detection capability of TC, and the sensitivity of the sensor reaches to −0.00155 ppm −1 with range of 5–20 ppm, and the LOD is 0.005 ppm. The proposed micro-structure POF sensor features easy fabrication and low-cost, which provides a new approach for TC detection.