Surface plasmon-enhanced gas sensing in single gold-peapodded silica nanowires

A Taiwan-based team led by Kuei-Hsien Chen has improved the room-temperature gas-sensing properties of silica nanowire-based systems by incorporating gold nanoparticles inside the nanowire in a ‘peas-in-a-pod’ manner. Upon shining light on the device, surface plasmon resonance occurs at gold nanoparticles that absorb the visible light (from a 532 nm laser) at room temperature. Under this irradiation, a gold-embedded silica nanowire undergoes photogeneration of electrons and holes at a higher rate than its plain silica counterpart. As a result, the nanowire's conductivity is enhanced and the sensing of oxygen at the wire's surface is facilitated by the molecule's interaction with photogenerated electrons, while its recovery (desorption) is improved by the presence of the holes. As neither gold nor silica nanoparticles are known to be toxic, the gold-silica nanowire system holds promise for measuring oxygen in biological and medical applications.