Multifunctional, flexible, and free-standing SERS-active AgNW filter foils


Demirtas Ö., Akdemir O., Coşkun Å., ÜNALAN H. E. , BEK A.

Nanophotonics VIII 2020, Virtual, Online, France, 6 - 10 April 2020, vol.11345 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 11345
  • Doi Number: 10.1117/12.2555803
  • City: Virtual, Online
  • Country: France
  • Keywords: surface-enhanced Raman spectroscopy, plasmon, silver nanowire filter foil, polyol synthesis, ATOMIC LAYER DEPOSITION, POLYOL SYNTHESIS, RAMAN, NANOPARTICLES, MONOLAYERS, MOLECULES, KINETICS

Abstract

© 2020 SPIE.In this work, we report the feasibility of the silver nanowire (AgNW) foils as highly-sensitive, reproducible and facile detection tools for surface-enhanced Raman spectroscopy (SERS) applications. These flexible and free-standing AgNW foils, fabricated by vacuum filtration method following a modified polyol synthesis of AgNWs, are adequately structured for both biological specimen filtering and trace amount of molecule detection simultaneously. The compatibility of AgNW foil in SERS is investigated by using a Raman active molecule of different steric volumes across the filter cross-section. We have shown that AgNW foils exhibit extremely strong SERS activity with detection limit up to 10-9 M of crystal violet (CV) molecule with 20% variation over ∼cm2 , revealing reliable homogeneity of the acquired signal. While naturally occurring polyvinylpyrrolidone (PVP) layer during polyol synthesis contribute to controlled aggregation, oxidation prevention, and size - shape control purposes, it also creates a major challenge for obtaining enormous enhancement factors. However, controlled thickness of aluminum oxide (Al2O3) coating on PVP@AgNW foils affords to achieve higher enhancement factors than the uncoated ones. What is interesting is that the maximum intensity is achieved from two cycles of Al2O3 deposited on AgNW foils. This is attributed to the two different origins: first, a higher adsorption affinity of CV molecules to Al2O3 layer than PVP layer; second, tunneling barrier formation against quantum tunneling effects.