A Portable RGB-Type Quantum Dot-Based Water Sensing Device for Heavy Metal Ion Detection

Abstract

Using fluorescent quantum dots to detect heavy metal ions in water resources has attracted extensive attention. However, bulky photoluminescence spectrometers are generally required to read the signals, which are not suitable for on-site detection. This study designed a portable RGB-type quantum dot-based water sensing device using semiconductor quantum dots (SQDs) and carbon quantum dots (CQDs) as probes to detect various heavy metal ions. The results generated from the device in general agree well with those obtained from photoluminescence spectroscopy, demonstrating that the device can effectively screen the presence of different heavy metal ions. Both the portable device and the photoluminescence spectrometer measurements confirmed that the SQDs used in this study could detect a lower concentration of heavy metal ions, but their fluorescence was quenched by a wide range of other ions at a higher testing concertation. In comparison, CQDs had better selectivity to Cadmium (Cd) ions. Our work verified the feasibility of the RGB-type quantum dot-based portable water sensing device, and the future work will focus on selecting a proper quantum dot material to achieve high selectivity and sensitivity simultaneously.