title: Sheath-flow microfluidic approach for combined surface enhanced Raman scattering and electrochemical detection.
abstract: The combination of hydrodynamic focusing with embedded capillaries in a microfluidic device is shown to enable both surface enhanced Raman scattering (SERS) and electrochemical characterization of analytes at nanomolar concentrations in flow. The approach utilizes a versatile polystyrene device that contains an encapsulated microelectrode and fluidic tubing, which is shown to enable straightforward hydrodynamic focusing onto the electrode surface to improve detection. A polydimethyslsiloxane (PDMS) microchannel positioned over both the embedded tubing and SERS active electrode (aligned ∼200 μm from each other) generates a sheath flow that confines the analyte molecules eluting from the embedded tubing over the SERS electrode, increasing the interaction between the Riboflavin (vitamin B2) and the SERS active electrode. The microfluidic device was characterized using finite element simulations, amperometry, and Raman experiments. This device shows a SERS and amperometric detection limit near 1 and 100 nM, respectively. This combination of SERS and amperometry in a single device provides an improved method to identify and quantify electroactive analytes over either technique independently.
authors: †University of Notre Dame, Department of Chemistry and Biochemistry, Notre Dame, Indiana 46556, United States.
authors: Matthew R
authors: MR
authors: Bailey
authors: ‡Saint Louis University, Department of Chemistry, St. Louis, Missouri 63103, United States.
authors: Amber M
authors: AM
authors: Pentecost
authors: ‡Saint Louis University, Department of Chemistry, St. Louis, Missouri 63103, United States.
authors: Asmira
authors: A
authors: Selimovic
authors: ‡Saint Louis University, Department of Chemistry, St. Louis, Missouri 63103, United States.
authors: R Scott
authors: RS
authors: Martin
authors: †University of Notre Dame, Department of Chemistry and Biochemistry, Notre Dame, Indiana 46556, United States.
authors: Zachary D
authors: ZD
authors: Schultz
mesh_terms: D055664:Electrochemical Techniques; D004566:Electrodes; D057446:Hydrodynamics; D046210:Microfluidic Analytical Techniques; D011137:Polystyrenes / Q000737:chemistry; D012256:Riboflavin / Q000032:analysis* / Q000378:metabolism; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
chemical_list: D011137:Polystyrenes; D012256:Riboflavin