Design and Modeling of SERS based Sensor Chips for Applications in Nanomedicine

摘要

In this work, we present surface enhanced Raman scattering (SERS) based sensor chips for applications in nanomedicine. Finite Difference Time Domain (FDTD) simulations in visible, infrared and near-infrared regimes were done to model electric field enhancement in the vicinity of plasmonic nanostructures. Some of the plasmonic nanostructures simulated were present bowtie nanohole arrays and bridged-bowtie nanohole arrays in a gold thin film. Surface enhanced Raman scattering (SERS) substrates based on these nanostructures exhibit large electromagnetic enhancement of SERS. We employ numerical simulations based on the finite difference time domain (FDTD) method to determine the electric field enhancement factors (EFs) and therefore the electromagnetic SERS enhancement factor for these SERS substrates. It was observed that the resonance wavelength of these arrays of nanoholes can be tuned by altering the size of the nanoholes. It was also observed that bridged-bowtie nanohole arrays exhibit very high electric field enhancement factors (EF) for multiple wavelengths. It was observed that bridged-bowtie nanohole arrays exhibit a highest electromagnetic SERS enhancement factor (EF) of ～10~9, which is orders of magnitude higher than what has been previously reported for nanohole arrays as SERS substrates. Hence, these nanostructures can provide SERS enhancement suitable for a few-molecule detection.