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

Özge Demirtas; Ozan Akdemir; Şahin Coşkun; H. Emrah Ünalan; Alpan Bek

doi:10.1117/12.2555803

1 April 2020 Multifunctional, flexible, and free-standing SERS-active AgNW filter foils

Özge Demirtas, Ozan Akdemir, Şahin Coşkun, H. Emrah Ünalan, Alpan Bek

Proceedings Volume 11345, Nanophotonics VIII; 113452F (2020) https://doi.org/10.1117/12.2555803
Event: SPIE Photonics Europe, 2020, Online Only

Abstract

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^-9M 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.

Conference Presentation

Citation Download Citation

Özge Demirtas, Ozan Akdemir, Şahin Coşkun, H. Emrah Ünalan, and Alpan Bek "Multifunctional, flexible, and free-standing SERS-active AgNW filter foils", Proc. SPIE 11345, Nanophotonics VIII, 113452F (1 April 2020); https://doi.org/10.1117/12.2555803

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