Fast and sensitive virus detection using a plasmonic sensor that integrates electrokinetically assisted sampling and surface-enhanced Raman scattering

We present a novel plasmonic biosensing method for on-chip detection on viral particles featuring a micro- electrode platform that integrates accelerated sampling of virus with surface-enhanced Raman scattering (SERS). We show experimentally that our approach can produce spectacular results owing to the unique incorporation of two key features: (1) Concentration amplification of virus on the SERS-active substrate; (2) Local plasmonic activity enhancement due to the targeted superimposition of silver nanoparticles on the captured virus sites. When tested for the detection of the M13 bacteriophage our "sandwich" assay yielded excellent reproducibility (signal variation <6%) and a very low limit of detection (1.13 x 102 pfu/ml). Compared with the performance of our standard SERS substrates, SERS signals stronger by at least one order of magnitude are typically achieved. In addition to experimental results, our work also includes finite element (COMSOL Multiphysics) and finite- difference time-domain (FDTD) simulations that provide insights into the mechanisms of concentration amplification and plasmonic activity enhancement, respectively.