Document Type
Article
Publication Date
2026
DOI
10.3390/photonics13090840
Publication Title
Photonics
Volume
13
Issue
9
Pages
840
Abstract
Gold-sputtered tapered optical fiber (Au-TOF) sensors were developed for high-sensitivity refractive-index (RI) detection using aqueous glucose standards spanning 1.33–1.41 RIU (0–50% w/v). The sensors were fabricated using a reproducible workflow combining flame-brushing tapering, plasma surface preparation, and rotational magnetron sputtering, enabling azimuthally uniform gold coatings without the use of thiol or sulfur linker chemistries. Two sputtering durations (24 s and 30 s) were investigated to examine thickness-dependent plasmonic coupling and sensing performance. Optical measurements were conducted using a broadband supercontinuum source and compact spectrometer within a 20 µL microfluidic sensing chamber. Increasing glucose concentration produced a monotonic decrease in transmission intensity and a systematic red shift of the resonance minimum, consistent with enhanced evanescent-field interaction at the gold–dielectric interface. Across four independent trials, the 24 s Au-TOF sensor exhibited sensitivities up to 985 nm/RIU, while the 30 s device achieved sensitivities up to 1590 nm/RIU with strong linearity (R² = 0.99). The enhanced sensitivity observed for the longer sputtering duration is attributed to improved gold film continuity and stronger plasmonic coupling. These results demonstrate a scalable, linker-free fabrication strategy for plasmonically enhanced tapered fiber sensors and establish the Au-TOF platform as a promising approach for label-free optical biosensing in compact microfluidic environments.
Original Publication Citation
Ujah, E., & Slaughter, G. (2026). Linker-free gold-sputtered tapered optical fiber plasmonic sensors for high-sensitivity refractive index detection in microfluidic platforms. Photonics, 13(9), Article 840. https://doi.org/10.3390/photonics13090840
Repository Citation
Ujah, E., & Slaughter, G. (2026). Linker-free gold-sputtered tapered optical fiber plasmonic sensors for high-sensitivity refractive index detection in microfluidic platforms. Photonics, 13(9), Article 840. https://doi.org/10.3390/photonics13090840
ORCID
0000-0002-4307-091X (Slaughter)
Included in
Biomedical Engineering and Bioengineering Commons, Electrical and Computer Engineering Commons, Equipment and Supplies Commons, Materials Science and Engineering Commons
Comments
© 2026 by the authors.
This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) License.
Data Availability Statement: Article states: "Data is contained within the article."