Template fabricated plasmonic nanoholes on analyte-sensitive substrates for real-time vapor sensing
Sensing with nanostructured plasmonic devices has become an important research field due to their proven ability to be extremely sensitive, compact, multiplexed, and compatible with low-cost fabrication techniques. In this paper, we employ a modified template stripping method to produce plasmonic nanohole arrays on analyte-sensitive substrates for real-time vapor sensing. The device operates by exploiting simultaneous plasmonic resonances within the substrate as well as within the vapor being tested. Because the substrate is in contact with vapor due to the open-hole geometry, red-shifts (air-side resonances) and blue-shifts (substrate-side resonances) are seen at the same time during exposure to <10 ppm ethanol vapor in nitrogen. We also show negative control experiments with similar concentrations of m-xylene, as well as multiplex sensing potential with chemically patterned substrates. Our devices could operate as low-cost gas sensors for environmental monitoring, security, or food safety.