▎ 摘　　要

NOVELTY - Sensor comprises substrate, graphene-based fluorescent layer stacked on substrate, and DNA probe for capturing metal ions, where the DNA probe is coupled with the fluorescent layer, and optionally in combination with metal ions. USE - The sensor is useful for detecting metal ion (claimed). DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) system for detecting metal ion comprising the above-mentioned sensor, optical unit for detecting fluorescence emitted from the graphene-based fluorescent layer, and detection unit for detecting metal ion by comparing fluorescent intensity detected from optical unit with standard fluorescent intensity, if the fluorescent intensity is lower than the standard fluorescent intensity, then the metal ion is detected; and (2) method for detecting the metal ion involves capturing metal ion by DNA probe which is coupled with the graphene-based fluorescent layer, and detecting metal ion by comparing fluorescent intensity which is measured after binding of metal ion to DNA probe with standard fluorescent intensity, if the fluorescent intensity is lower than the standard fluorescent intensity, then the metal ion is detected.