title: Millimeter-Sized Suspended Plasmonic Nanohole Arrays for Surface-Tension-Driven Flow-Through SERS.
abstract: We present metallic nanohole arrays fabricated on suspended membranes as an optofluidic substrate. Millimeter-sized suspended nanohole arrays were fabricated using nanoimprint lithography. We demonstrate refractive-index-based tuning of the optical spectra using a sucrose solution for the optimization of SERS signal intensity, leading to a Raman enhancement factor of 107. Furthermore, compared to dead-ended nanohole arrays, suspended nanohole arrays capable of flow-through detection increased the measured SERS signal intensity by 50 times. For directed transport of analytes, we present a novel methodology utilizing surface tension to generate spontaneous flow through the nanoholes with flow rates of 1 μL/min, obviating the need for external pumps or microfluidic interconnects. Using this method for SERS, we obtained a 50 times higher signal as compared to diffusion-limited transport and could detect 100 pM 4-mercaptopyridine. The suspended nanohole substrates presented herein possess a uniform and reproducible geometry and show the potential for improved analyte transport and SERS detection.
authors: Department of Electrical and Computer Engineering, and Department of Biomedical Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Shailabh
authors: S
authors: Kumar
authors: Department of Electrical and Computer Engineering, and Department of Biomedical Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Sudhir
authors: S
authors: Cherukulappurath
authors: Department of Electrical and Computer Engineering, and Department of Biomedical Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Timothy W
authors: TW
authors: Johnson
authors: Department of Electrical and Computer Engineering, and Department of Biomedical Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Sang-Hyun
authors: SH
authors: Oh