SERS Barcode Libraries: A Microfluidic Approach

Microfluidic technologies have emerged as advanced tools for surface-enhanced Raman spectroscopy (SERS). They have proved to be particularly appealing for in situ and real-time detection of analytes at extremely low concentrations and down to the 10 × 10^-15 m level. However, the ability to prepare reconfigurable and reusable devices endowing multiple detection capabilities is an unresolved challenge. Herein, a microfluidic-based method that allows an extraordinary spatial control over the localization of multiple active SERS substrates in a single microfluidic channel is presented. It is shown that this technology provides for exquisite control over analyte transport to specific detection points, while avoiding cross-contamination; a feature that enables the simultaneous detection of multiple analytes within the same microfluidic channel. Additionally, it is demonstrated that the SERS substrates can be rationally designed in a straightforward manner and that they allow for the detection of single molecules (at concentrations as low as 10^-14 m). Finally, it is shown that rapid etching and reconstruction of SERS substrates provides for reconfigurable and reusable operation.