Issue 24, 2021

Molecular trace detection in liquids using refocusing optical feedback by a silver-coated capillary

Abstract

Surface-enhanced Raman scattering (SERS) has been widely used owing to its high sensitivity and rapid response. In particular, 3D SERS-active platforms greatly extend the interaction area and ensure the ability to directly detect trace amounts of molecules in liquids. A silver-coated capillary, with the ability of liquid sampling and light guiding, provides a new platform for high-performance SERS substrates. In this paper, the silver mirror reaction was used for coating silver on the outer wall of the capillary. PDMS was used as a coating material to protect the silver film. Because of the silver coating, Mie scattering and Raman scattering in the liquid channel can be refocused and reflected back which greatly reduces the propagation loss and extends the interaction length. An enhancement factor as high as 108 and a detection limit of 10−10 M of rhodamine 6G in aqueous solution have been achieved. Moreover, the SERS intensity is homogeneous across the end face of the liquid channel, with the relative standard deviation (RSD) value changing within 7%. The large area and high homogeneity greatly reduce the requirement of light coupling precision and liquid injection pressure. Using a common flange optical fiber connector, the capillary can be simply connected and aligned with a multimode fiber with a detection limit of 10−8 M. The experiment results show great potential for the development of an optofluidic integrated system in the future.

Graphical abstract: Molecular trace detection in liquids using refocusing optical feedback by a silver-coated capillary

Article information

Article type
Paper
Submitted
28 jul. 2021
Accepted
05 oct. 2021
First published
05 oct. 2021
This article is Open Access
Creative Commons BY-NC license

Nanoscale Adv., 2021,3, 6934-6939

Molecular trace detection in liquids using refocusing optical feedback by a silver-coated capillary

C. Kang, Z. Sun, X. Fang, L. Zha, Y. Han, H. Liu, J. Guo and X. Zhang, Nanoscale Adv., 2021, 3, 6934 DOI: 10.1039/D1NA00593F

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