Solid State Carbon Dots-Based Sensor Using Optical Microfiber for Ferric Ion Detection

Typically, carbon dots-based sensors are based on the changes in fluorometric emissions due to the presence of a specific analyte. The changes in fluorescence intensities are then correlated to the amount of analyte present. However, this sensing method is usually carried out in the liquid phase and often requires an expensive and bulky spectrometer. Moreover, the changes in fluorescence emission intensities are visually subjective and can only be used as a qualitative sensor. To circumvent this issue, we proposed an alternative by adopting an optical microfiber sensor functionalized with carbon dots via EDC-NHS chemistry for ferric ion detection in an aqueous sample. Here, the carbon dots will serve as a chelating agent which induces a phase shift in the output light spectrum upon binding with ferric ions. By measuring the phase difference between the input light and output light, the amount of ferric ion present can be identified. To the best of our knowledge, this is the first report on employing CDs as a chelating agent for the detection of ferric ion.