Integrated Plasmonic Biosensors with Microfluidics

Surface-enhanced Raman scattering (SERS) and surface plasmon resonance (SPR) detection are two key surface plasmon techniques that will ultimately enable single-molecule-level chemical and biological sensors.  To resolve the reproducibility issue of stochastically aggregated colloidal nanoparticles which are commonly used in SERS and SPR detection, various periodic plasmonic nanostructures with well-defined SP properties have been broadly exploited.  Unfortunately, the development and implementation of these nanostructured SP substrates have been greatly impeded by expensive and painstaking top-down nanofabrication (e.g., electron-beam lithography and focused ion-beam), which limit the available sample size to less than 1 mm². Here we report a robust bottom-up nanofabrication platform that provides a much simpler, faster, and inexpensive alternative to nanolithography in creating a large variety of highly ordered plasmonic nanostructures. This platform combines the simplicity and cost benefits of bottom-up colloidal self-assembly with the scalability and compatibility of top-down microfabrication.  We have demonstrated the capability of this novel methodology in creating highly sensitive and reproducible SERS and SPR biosensors over wafer-sized areas. Most importantly, this novel nanofabrication platform is compatible with standard microfabrication, enabling on-wafer integration of SP biosensors with conventional microfluidic devices.