Plasmonic sensors are devices that utilize the unique properties of surface plasmons, which are coherent oscillations of electrons at the surface of a metal when excited by light. These sensors can detect minute changes in the environment, such as the presence of specific molecules, by measuring shifts in the light that interacts with the surface. This makes them highly sensitive and useful for applications in fields like biomedical diagnostics and environmental monitoring. The technology behind plasmonic sensors often involves materials like gold or silver, which are known for their ability to support surface plasmon resonance. When light hits these materials, it can enhance signals, allowing for the detection of low concentrations of substances. This capability makes plasmonic sensors valuable tools in chemical analysis and food safety testing.