SERS-active Capillary

Vapor phase detection using SERS exists only limited knowledge, as compared to the broadly investigated filed of SERS in liquid phase. I have lead the development of novel flow-through surface-enhanced Raman scattering (SERS) platforms using gold nanoparticle immobilized multi-hole capillaries for rapid and sensitive vapor detection. The multi-hole capillaries consisting of thousands of micron-sized flow-through channels provide many unique characteristics for vapor detection. Most importantly, its 3-dimensional SERS-active micro-/nano structures make available multi-layered assembly of Au-NPs, which greatly increase SERS-active surface area within a focal volume of excitation and collection, thus improving the detection sensitivity. In addition, the multi-hole capillary’s inherent longitudinal channels offer rapid and convenient vapor delivery, yet its micron-sized holes increase the interaction between vapor molecules and SERS-active substrate. Experimentally, rapid pyridine vapor detection (within 1 second of exposure) and ultrasensitive 4-nitrophenol vapor detection (at a sub-ppb level) were successfully achieved in open air at room temperature. Such an ultrasensitive SERS platform enabled, for the first time, the investigation of both pyridine and 4-nitrophenol vapor adsorption isotherms at a very low concentration. Type I and Type V behaviors of the International Union of Pure and Applied Chemistry isotherm were well observed, respectively.