Fabrication of Optical Fiber pH Sensor Based on Near-Infrared (NIR) Quantum Dots

Abstract

Quantum dots, nano-sized semiconductors, have shown various peculiar optical and electrical properties. In recent years several researches on the synthesis and application of quantum dots have been carried out and achieved great progresses. In our previous studies, several kinds of sensors have been fabricated using quantum dots. However, most of them are using cadmium based quantum dots which emit fluorescence in visible wave lengths. As the cadmium element can be released slowly in biological reaction, the use of cadmium based quantum dots in the medical area is limited. In this paper, we prepared optical fiber pH sensor using CuInS/ZnS near infrared quantum dots. The quantum dots were immobilized on the surface of tapered optical fiber as probes of pH. The surface of the optical fiber was silanized to enhance covalent bonds between quantum dot and optical fiber. The fluorescent intensity of the quantum dots on optical fiber shows a linear relation with pH.