An optical fiber fluorescence pH sensor based on CdTe quantum dots

The pH value is one of the essential parameters of a solution, serving as a significant indicator in the fields of chemistry, biology, environment, and others. Monitoring the pH value of liquids is often necessary in many situations. This study combines CdTe quantum dots and optical fiber for pH detection. CdTe quantum dots are a novel fluorescent material with high fluorescence intensity, which varies in fluorescence intensity in solutions with different pH values. The sensing structure is created by connecting an exposed core fiber with a multimode fiber through fusion splicing and encasing them in a glass tube. When the tested solution mixes with CdTe quantum dots and flows through the sensing structure, the excited fluorescence signal is directly coupled into the exposed core of the exposed core fiber. The fluorescence signal travels along the optical fiber and is detected. We used this sensing structure for PH detection in different solutions. Experimental results indicate a linear relationship between pH values ranging from 5.0 to 11.0 and relative fluorescence intensity. The detection limit is 0.17pH, and the response time is short. The sensor exhibits good stability and repeatability. The designed sensor structure is simple, user-friendly, and reusable, providing a powerful tool for future environmental and health monitoring.