Trace Detection of Cd²⁺ Ions Based on α-Fe₂O₃@MoS₂ Functionalized OMC Ultra-Sensitive Fiber Optic Sensor

In this article, an optical microfiber coupler (OMC) ultrasensitive fiber optic sensor based on $\alpha $ -Fe ₂ O ₃ @MoS ₂ functionalization is proposed for ultralow concentration specificity detection of cadmium ions (Cd ²⁺ . First, the optimal diameter and optimal spectrum of OMC were explored experimentally. Second, the functional group functionalization method is used to closely integrate the α-Fe ₂ O ₃ @MoS ₂ with the OMC cone. Finally, the fiber optic sensor was designed to achieve ultralow trace detection of the Cd $^{{2}+}$ . The results show that in the range of 0– $1 \mu \text{M}$ , the maximum detection sensitivity of Cd $^{{2}+}$ is 9758.92 nm/ $\mu \text{M}$ , the linearity is good, about 0.976, and the minimum detection concentration is $0.0001 \mu \text{M}$ (about 0.0182 ppb). At the same time, the sensor also has good performance in terms of responsiveness, selectivity, reversibility, and stability. It has potential applications in the detection of Cd $^{{2}+}$ in different solution environments.